diff -up build/pkgs/sagetex/src/remote-sagetex.py.orig build/pkgs/sagetex/src/remote-sagetex.py

--- build/pkgs/sagetex/src/remote-sagetex.py.orig	2020-08-12 02:35:31.000000000 -0600

+++ build/pkgs/sagetex/src/remote-sagetex.py	2020-10-30 14:03:01.286904419 -0600

@@ -24,12 +24,11 @@

 ## You should have received a copy of the GNU General Public License along

 ## with this program.  If not, see <http://www.gnu.org/licenses/>.

 ## 

-from __future__ import print_function

 import json

 import sys

 import time

 import re

-import urllib

+import urllib.request, urllib.parse, urllib.error

 import hashlib

 import os

 import os.path

@@ -156,7 +155,7 @@ class RemoteSage:

                                    '\n*(?P<output>.*)', re.DOTALL)

         self._404 = re.compile('404 Not Found')

         self._session = self._get_url('login',

-                                    urllib.urlencode({'username': user,

+                                    urllib.parse.urlencode({'username': user,

                                     'password':

                                     password}))['session']

         self._codewrap = """try:

@@ -176,18 +175,18 @@ except:

             _p_.save(filename=plotfilename, **kwargs)""")

     def _encode(self, d):

-        return 'session={0}&'.format(self._session) + urllib.urlencode(d)

+        return 'session={0}&'.format(self._session) + urllib.parse.urlencode(d)

     def _get_url(self, action, u):

-        with closing(urllib.urlopen(self._srv + '/simple/' + action +

-                                    '?' + u)) as h:

+        with closing(urllib.request.urlopen(self._srv + '/simple/' + action +

+                                            '?' + u)) as h:

             data = self._response.match(h.read())

             result = json.loads(data.group('header'))

             result['output'] = data.group('output').rstrip()

         return result

     def _get_file(self, fn, cell, ofn=None):

-        with closing(urllib.urlopen(self._srv + '/simple/' + 'file' + '?' +

+        with closing(urllib.request.urlopen(self._srv + '/simple/' + 'file' + '?' +

                      self._encode({'cell': cell, 'file': fn}))) as h:

             myfn = ofn if ofn else fn

             data = h.read()

@@ -277,13 +276,13 @@ if login_info_file:

                     password = get_val(line)

 if not server:

-    server = raw_input('Enter server: ')

+    server = input('Enter server: ')

 if not server.startswith('http'):

     server = 'https://' + server

 if not username:

-    username = raw_input('Enter username: ')

+    username = input('Enter username: ')

 if not password:

     from getpass import getpass

diff -up build/pkgs/sagetex/src/sagetexparse.py.orig build/pkgs/sagetex/src/sagetexparse.py

--- build/pkgs/sagetex/src/sagetexparse.py.orig	2020-08-12 02:35:31.000000000 -0600

+++ build/pkgs/sagetex/src/sagetexparse.py	2020-10-30 14:03:01.286904419 -0600

@@ -132,7 +132,7 @@ class SageCodeExtractor():

   def plotout(self, s, l, t):

     self.result += '# \\sageplot{} from line %s:\n' % lineno(l, s)

-    if t.format is not '':

+    if t.format != '':

       self.result += '# format: %s' % t.format[0][1:-1] + '\n'

     self.result += t.code[1:-1] + '\n\n'

diff -up src/sage/cpython/debugimpl.c.orig src/sage/cpython/debugimpl.c

--- src/sage/cpython/debugimpl.c.orig	2020-10-24 11:37:59.000000000 -0600

+++ src/sage/cpython/debugimpl.c	2020-10-30 14:03:01.299904398 -0600

@@ -148,6 +148,7 @@ static void _type_debug(PyTypeObject* tp

     printf("  tp_basicsize: %ld\n", (long)tp->tp_basicsize);

     printf("  tp_itemsize: %ld\n", (long)tp->tp_itemsize);

     printf("  tp_dictoffset: %ld\n", (long)tp->tp_dictoffset);

+    printf("  tp_vectorcall_offset: %ld\n", (long)tp->tp_vectorcall_offset);

     if HAVE_WEAKREFS(tp)

     {

         printf("  tp_weaklistoffset: %ld\n", (long)tp->tp_weaklistoffset);

@@ -178,7 +179,6 @@ static void _type_debug(PyTypeObject* tp

     attr_pointer(tp_free);

     attr_pointer_meth(tp_repr, "__repr__");

-    attr_pointer(tp_print);

     attr_pointer_meth(tp_hash, "__hash__");

     attr_pointer_meth(tp_call, "__call__");

     attr_pointer_meth(tp_str, "__str__");

diff -up src/sage/cpython/debug.pyx.orig src/sage/cpython/debug.pyx

--- src/sage/cpython/debug.pyx.orig	2020-10-24 11:37:59.000000000 -0600

+++ src/sage/cpython/debug.pyx	2020-10-30 14:03:01.300904396 -0600

@@ -232,6 +232,7 @@ def type_debug(cls):

           tp_basicsize: 16

           tp_itemsize: 0

           tp_dictoffset: 0

+          tp_vectorcall_offset: 0

           tp_weaklistoffset: 0

           tp_base (__base__): NULL

           tp_bases (__bases__): tuple:

@@ -259,7 +260,6 @@ def type_debug(cls):

           tp_dealloc (__dealloc__): 0x7fc57d757010

           tp_free: PyObject_Del

           tp_repr (__repr__): 0x7fc57d75b990

-          tp_print: NULL

           tp_hash (__hash__): _Py_HashPointer

           tp_call (__call__): NULL

           tp_str (__str__): 0x7fc57d757020

diff -up src/sage/geometry/triangulation/point_configuration.py.orig src/sage/geometry/triangulation/point_configuration.py

--- src/sage/geometry/triangulation/point_configuration.py.orig	2020-10-24 11:37:59.000000000 -0600

+++ src/sage/geometry/triangulation/point_configuration.py	2020-10-30 14:03:01.301904394 -0600

@@ -619,11 +619,11 @@ class PointConfiguration(UniqueRepresent

             ['{{0,1,2,4},{1,2,3,4}}']

         """

         timeout = 600

-        proc = pexpect.spawn(executable, timeout=timeout)

+        proc = pexpect.spawn(executable, timeout=timeout, encoding='utf-8')

         proc.expect(r'Evaluating Commandline Options \.\.\.')

         proc.expect(r'\.\.\. done\.')

         proc.setecho(0)

-        assert proc.readline().strip() == b''

+        assert proc.readline().strip() == ''

         if verbose:

             print("#### TOPCOM input ####")

diff -up src/sage/interfaces/frobby.py.orig src/sage/interfaces/frobby.py

--- src/sage/interfaces/frobby.py.orig	2020-10-24 11:37:59.000000000 -0600

+++ src/sage/interfaces/frobby.py	2020-10-30 14:03:02.534902319 -0600

@@ -79,7 +79,7 @@ class Frobby:

             print("Frobby command: ", repr(command))

             print("Frobby input:\n", input)

-        process = Popen(command, stdin = PIPE, stdout = PIPE, stderr = PIPE)

+        process = Popen(command, stdin = PIPE, stdout = PIPE, stderr = PIPE, encoding='utf-8')

         if input:

             frinput = str_to_bytes(input)

         else:

diff -up src/sage/interfaces/gfan.py.orig src/sage/interfaces/gfan.py

--- src/sage/interfaces/gfan.py.orig	2020-10-24 11:37:59.000000000 -0600

+++ src/sage/interfaces/gfan.py	2020-10-30 14:11:30.550047499 -0600

@@ -62,7 +62,7 @@ class Gfan(object):

             print("gfan input:\n%s" % I)

         gfan_processes = Popen(cmd, stdin=PIPE, stdout=PIPE, stderr=PIPE,

-                               encoding='latin-1')

+                               encoding='utf-8')

         ans, err = gfan_processes.communicate(input=I)

         # sometimes, gfan outputs stuff to stderr even though everything is fine

diff -up src/sage/interfaces/latte.py.orig src/sage/interfaces/latte.py

--- src/sage/interfaces/latte.py.orig	2020-10-24 11:37:59.000000000 -0600

+++ src/sage/interfaces/latte.py	2020-10-30 14:03:03.974899895 -0600

@@ -152,6 +152,7 @@ def count(arg, ehrhart_polynomial=False,

     latte_proc = Popen(args,

                        stdin=PIPE, stdout=PIPE,

                        stderr=(None if verbose else PIPE),

+                       encoding='utf-8',

                        cwd=str(SAGE_TMP))

     ans, err = latte_proc.communicate(arg)

@@ -364,6 +365,7 @@ def integrate(arg, polynomial=None, algo

     latte_proc = Popen(args,

                        stdin=PIPE, stdout=PIPE,

                        stderr=(None if verbose else PIPE),

+                       encoding='utf-8',

                        cwd=str(SAGE_TMP))

     ans, err = latte_proc.communicate(arg)

diff -up src/sage/interfaces/sagespawn.pyx.orig src/sage/interfaces/sagespawn.pyx

--- src/sage/interfaces/sagespawn.pyx.orig	2020-10-24 11:37:59.000000000 -0600

+++ src/sage/interfaces/sagespawn.pyx	2020-10-30 14:03:03.975899894 -0600

@@ -1,6 +1,6 @@

 """

 Sage wrapper around pexpect's ``spawn`` class and

-the ptyprocess's ``PtyProcess`` class.

+the ptyprocess's ``PtyProcessUnicode`` class.

 AUTHOR:

@@ -21,7 +21,7 @@ AUTHOR:

 #*****************************************************************************

 from pexpect import *

-from ptyprocess import PtyProcess

+from ptyprocess import PtyProcessUnicode

 from cpython.ref cimport Py_INCREF

 from libc.signal cimport *

@@ -30,7 +30,6 @@ from posix.unistd cimport getpid, getpgi

 from time import sleep

-from sage.cpython.string cimport str_to_bytes

 from sage.interfaces.process cimport ContainChildren

@@ -173,7 +172,7 @@ class SageSpawn(spawn):

         return ret

-class SagePtyProcess(PtyProcess):

+class SagePtyProcess(PtyProcessUnicode):

     def close(self, force=None):

         """

         Quit the child process: send the quit string, close the

@@ -194,11 +193,7 @@ class SagePtyProcess(PtyProcess):

             if self.quit_string is not None:

                 try:

                     # This can fail if the process already exited

-                    # PtyProcess.write takes bytes; ideally we would use

-                    # an encoding picked specifically for the target process

-                    # but the default (UTF-8) will do now, since I don't

-                    # think we have any non-ASCII quit_strings anyways.

-                    self.write(str_to_bytes(self.quit_string))

+                    self.write(self.quit_string)

                 except (OSError, IOError):

                     pass

             self.fileobj.close()

diff -up src/sage/libs/coxeter3/coxeter.pyx.orig src/sage/libs/coxeter3/coxeter.pyx

--- src/sage/libs/coxeter3/coxeter.pyx.orig	2020-10-24 11:37:59.000000000 -0600

+++ src/sage/libs/coxeter3/coxeter.pyx	2020-10-30 14:03:03.976899892 -0600

@@ -37,7 +37,7 @@ cdef class String:

         EXAMPLES::

             sage: from sage.libs.coxeter3.coxeter import String       # optional - coxeter3

-            sage: s = String("hello"); s                              # optional - coxeter3

+            sage: s = String(b"hello"); s                             # optional - coxeter3

             hello

             sage: del s                                               # optional - coxeter3

         """

@@ -48,11 +48,11 @@ cdef class String:

         EXAMPLES::

             sage: from sage.libs.coxeter3.coxeter import String       # optional - coxeter3

-            sage: s = String('Hi')                                    # optional - coxeter3

+            sage: s = String(b'Hi')                                   # optional - coxeter3

             sage: s                                                   # optional - coxeter3

             Hi

         """

-        return bytes_to_str(self.x.ptr())

+        return self.x.ptr().decode('utf-8')

     def __hash__(self):

         """

@@ -64,7 +64,7 @@ cdef class String:

         EXAMPLES::

             sage: from sage.libs.coxeter3.coxeter import String        # optional - coxeter3

-            sage: s = String('hello')                                  # optional - coxeter3

+            sage: s = String(b'hello')                                 # optional - coxeter3

             sage: hash(s) == hash('hello')                             # optional - coxeter3

             True

         """

@@ -75,9 +75,9 @@ cdef class String:

         EXAMPLES::

             sage: from sage.libs.coxeter3.coxeter import String        # optional - coxeter3

-            sage: ta1 = String('A')                                    # optional - coxeter3

-            sage: ta2 = String('A')                                    # optional - coxeter3

-            sage: tb = String('b')                                     # optional - coxeter3

+            sage: ta1 = String(b'A')                                   # optional - coxeter3

+            sage: ta2 = String(b'A')                                   # optional - coxeter3

+            sage: tb = String(b'b')                                    # optional - coxeter3

             sage: ta1 == ta2                                           # optional - coxeter3

             True

             sage: tb != ta1                                            # optional - coxeter3

@@ -113,7 +113,7 @@ cdef class String:

         EXAMPLES::

             sage: from sage.libs.coxeter3.coxeter import String       # optional - coxeter3

-            sage: s = String('Hi')                                    # optional - coxeter3

+            sage: s = String(b'Hi')                                   # optional - coxeter3

             sage: len(s)                                              # optional - coxeter3

             2

         """

@@ -124,7 +124,7 @@ cdef class String:

         EXAMPLES::

             sage: from sage.libs.coxeter3.coxeter import String       # optional - coxeter3

-            sage: s = String('Hi')                                    # optional - coxeter3

+            sage: s = String(b'Hi')                                   # optional - coxeter3

             sage: TestSuite(s).run()                                  # optional - coxeter3

         """

         return (String, (repr(self),) )

@@ -138,7 +138,7 @@ cdef class Type:

         EXAMPLES::

             sage: from sage.libs.coxeter3.coxeter import Type         # optional - coxeter3

-            sage: t = Type('A'); t                                    # optional - coxeter3

+            sage: t = Type(b'A'); t                                   # optional - coxeter3

             A

             sage: del t                                               # optional - coxeter3

         """

@@ -149,7 +149,7 @@ cdef class Type:

         EXAMPLES::

             sage: from sage.libs.coxeter3.coxeter import Type         # optional - coxeter3

-            sage: t = Type('A'); t                                    # optional - coxeter3

+            sage: t = Type(b'A'); t                                   # optional - coxeter3

             A

         """

         return bytes_to_str(self.x.name().ptr())

@@ -159,7 +159,7 @@ cdef class Type:

         EXAMPLES::

             sage: from sage.libs.coxeter3.coxeter import Type         # optional - coxeter3

-            sage: t = Type('A')                                       # optional - coxeter3

+            sage: t = Type(b'A')                                      # optional - coxeter3

             sage: t.name()                                            # optional - coxeter3

             A

         """

@@ -175,8 +175,8 @@ cdef class Type:

         EXAMPLES::

             sage: from sage.libs.coxeter3.coxeter import Type          # optional - coxeter3

-            sage: a = Type('A')                                        # optional - coxeter3

-            sage: b = Type('B')                                        # optional - coxeter3

+            sage: a = Type(b'A')                                       # optional - coxeter3

+            sage: b = Type(b'B')                                       # optional - coxeter3

             sage: hash(a) == hash(b)                                   # optional - coxeter3

             False

             sage: d = {a: 1, b: 2}                                     # optional - coxeter3

@@ -188,9 +188,9 @@ cdef class Type:

         EXAMPLES::

             sage: from sage.libs.coxeter3.coxeter import Type          # optional - coxeter3

-            sage: ta1 = Type('A')                                      # optional - coxeter3

-            sage: ta2 = Type('A')                                      # optional - coxeter3

-            sage: tb = Type('b')                                       # optional - coxeter3

+            sage: ta1 = Type(b'A')                                     # optional - coxeter3

+            sage: ta2 = Type(b'A')                                     # optional - coxeter3

+            sage: tb = Type(b'b')                                      # optional - coxeter3

             sage: ta1 == ta2                                           # optional - coxeter3

             True

             sage: tb != ta1                                            # optional - coxeter3

@@ -224,7 +224,7 @@ cdef class Type:

         EXAMPLES::

             sage: from sage.libs.coxeter3.coxeter import Type           # optional - coxeter3

-            sage: t = Type('A')                                         # optional - coxeter3

+            sage: t = Type(b'A')                                        # optional - coxeter3

             sage: TestSuite(t).run()                                    # optional - coxeter3

         """

         return (Type, (repr(self), ))

@@ -268,7 +268,7 @@ cdef class CoxGroup(SageObject):

                 pass

             type = type.lower()

-        type = 'B' if type == 'C' else type

+        type = b'B' if type == 'C' else type.encode('utf-8')

         if rank == 0:

             raise NotImplementedError("Coxeter group of type ['A',0] using Coxeter 3 not yet implemented")

diff -up src/sage/misc/sageinspect.py.orig src/sage/misc/sageinspect.py

--- src/sage/misc/sageinspect.py.orig	2020-11-01 10:38:08.203022437 -0700

+++ src/sage/misc/sageinspect.py	2020-11-01 10:43:43.355143620 -0700

@@ -463,12 +463,9 @@ class SageArgSpecVisitor(ast.NodeVisitor

         """

         return node.id

-    def visit_NameConstant(self, node):

-        """

-        Visit a Python AST :class:`ast.NameConstant` node.

-

-        This is an optimization added in Python 3.4 for the special cases

-        of True, False, and None.

+    def visit_Constant(self, node):

+        r"""

+        Visit a Python AST :class:`ast.Constant` node.

         INPUT:

@@ -476,17 +473,21 @@ class SageArgSpecVisitor(ast.NodeVisitor

         OUTPUT:

-        - None, True, False.

+        - the boolean, number, or string the ``node`` represents

         EXAMPLES::

-            sage: import ast, sage.misc.sageinspect as sms  # py3

-            sage: visitor = sms.SageArgSpecVisitor()  # py3

-            sage: vis = lambda x: visitor.visit_NameConstant(ast.parse(x).body[0].value)  # py3

-            sage: [vis(n) for n in ['True', 'False', 'None']]  # py3

+            sage: import ast, sage.misc.sageinspect as sms

+            sage: visitor = sms.SageArgSpecVisitor()

+            sage: vis = lambda x: visitor.visit_Constant(ast.parse(x).body[0].value)

+            sage: [vis(n) for n in ['True', 'False', 'None']]

             [True, False, None]

-            sage: [type(vis(n)) for n in ['True', 'False', 'None']]  # py3

+            sage: [type(vis(n)) for n in ['True', 'False', 'None']]

             [<type 'bool'>, <type 'bool'>, <type 'NoneType'>]

+            sage: [vis(s) for s in ['"abstract"', "u'syntax'", r'''r"tr\ee"''']]

+            ['abstract', u'syntax', 'tr\\ee']

+            sage: [vis(n) for n in ['123', '0.0']]

+            [123, 0.0]

         """

         return node.value

@@ -520,57 +521,6 @@ class SageArgSpecVisitor(ast.NodeVisitor

         """

         return node.arg

-    def visit_Num(self, node):

-        """

-        Visit a Python AST :class:`ast.Num` node.

-

-        INPUT:

-

-        - ``node`` - the node instance to visit

-

-        OUTPUT:

-

-        - the number the ``node`` represents

-

-        EXAMPLES::

-

-            sage: import ast, sage.misc.sageinspect as sms

-            sage: visitor = sms.SageArgSpecVisitor()

-            sage: vis = lambda x: visitor.visit_Num(ast.parse(x).body[0].value)

-            sage: [vis(n) for n in ['123', '0.0', str(-pi.n())]]  # py2

-            [123, 0.0, -3.14159265358979]

-            sage: [vis(n) for n in ['123', '0.0']]  # py3

-            [123, 0.0]

-

-        .. NOTE::

-

-            On Python 3 negative numbers are parsed first, for some reason, as

-            a UnaryOp node.

-        """

-        return node.n

-

-    def visit_Str(self, node):

-        r"""

-        Visit a Python AST :class:`ast.Str` node.

-

-        INPUT:

-

-        - ``node`` - the node instance to visit

-

-        OUTPUT:

-

-        - the string the ``node`` represents

-

-        EXAMPLES::

-

-            sage: import ast, sage.misc.sageinspect as sms

-            sage: visitor = sms.SageArgSpecVisitor()

-            sage: vis = lambda x: visitor.visit_Str(ast.parse(x).body[0].value)

-            sage: [vis(s) for s in ['"abstract"', "u'syntax'", r'''r"tr\ee"''']]

-            ['abstract', u'syntax', 'tr\\ee']

-        """

-        return node.s

-

     def visit_List(self, node):

         """

         Visit a Python AST :class:`ast.List` node.

diff -up src/sage/plot/plot3d/plot3d.py.orig src/sage/plot/plot3d/plot3d.py

--- src/sage/plot/plot3d/plot3d.py.orig	2020-10-24 11:37:59.000000000 -0600

+++ src/sage/plot/plot3d/plot3d.py	2020-10-30 14:24:36.813732073 -0600

@@ -186,7 +186,7 @@ class _Coordinates(object):

             sage: arb((x+z,y*z,z), z, (x,y))

             Arbitrary Coordinates coordinate transform (z in terms of x, y)

         """

-        all_vars = sage_getargspec(self.transform).args[1:]

+        all_vars = inspect.getfullargspec(self.transform)[0][1:]

         if set(all_vars) != set(indep_vars + [dep_var]):

             raise ValueError('variables were specified incorrectly for this coordinate system; incorrect variables were %s'%list(set(all_vars).symmetric_difference(set(indep_vars+[dep_var]))))

         self.dep_var = dep_var

diff -up src/sage/rings/integer.pyx.orig src/sage/rings/integer.pyx

--- src/sage/rings/integer.pyx.orig	2020-10-24 11:37:59.000000000 -0600

+++ src/sage/rings/integer.pyx	2020-10-30 14:03:05.737896928 -0600

@@ -7093,7 +7093,7 @@ cdef int mpz_set_str_python(mpz_ptr z, c

         x += 1  # Strip spaces

     # Disallow a sign here

-    if x[0] == '-' or x[0] == '+':

+    if x[0] == c'-' or x[0] == c'+':

         x = ""  # Force an error below

     assert base >= 2

diff -up src/sage/rings/polynomial/pbori/pbori.pyx.orig src/sage/rings/polynomial/pbori/pbori.pyx

--- src/sage/rings/polynomial/pbori/pbori.pyx.orig	2020-10-24 11:37:59.000000000 -0600

+++ src/sage/rings/polynomial/pbori/pbori.pyx	2020-11-05 15:44:02.756454276 -0700

@@ -4800,8 +4800,7 @@ cdef class PolynomialConstruct:

             # So, it is just a conversion. [Simon King]

             return (<BooleanPolynomialRing>ring)._element_constructor_(x)

-        raise TypeError("Cannot generate Boolean polynomial from %s , %s" %

-                        (type(x), type(ring)))

+        raise TypeError(f"Cannot generate Boolean polynomial from {type(x)}, {type(ring)}")

 cdef class MonomialConstruct:

diff -up src/sage/rings/real_mpfi.pyx.orig src/sage/rings/real_mpfi.pyx

--- src/sage/rings/real_mpfi.pyx.orig	2020-10-30 11:34:28.078977132 -0600

+++ src/sage/rings/real_mpfi.pyx	2020-10-30 14:03:09.088891288 -0600

@@ -1955,12 +1955,12 @@ cdef class RealIntervalFieldElement(Ring

         cdef long digits

         digits = strlen(lower_s)

-        if lower_s[0] == '-':

+        if lower_s[0] == c'-':

             digits -= 1

         lower_expo -= digits

         digits = strlen(upper_s)

-        if upper_s[0] == '-':

+        if upper_s[0] == c'-':

             digits -= 1

         upper_expo -= digits

@@ -2129,7 +2129,7 @@ cdef class RealIntervalFieldElement(Ring

             raise MemoryError("Unable to allocate memory for the mantissa of an interval")

         mpz_get_str(tmp_cstr, base, lower_mpz)

         digits = strlen(tmp_cstr)

-        if tmp_cstr[0] == '-':

+        if tmp_cstr[0] == c'-':

             digits -= 1

             mant_string = bytes_to_str(tmp_cstr+1)

             sign_string = bytes_to_str(b'-')

diff -up src/sage/rings/real_mpfr.pyx.orig src/sage/rings/real_mpfr.pyx

--- src/sage/rings/real_mpfr.pyx.orig	2020-10-24 11:37:59.000000000 -0600

+++ src/sage/rings/real_mpfr.pyx	2020-11-05 15:44:02.769454276 -0700

@@ -2091,7 +2091,7 @@ cdef class RealNumber(sage.structure.ele

         if s is NULL:

             raise RuntimeError("unable to convert an mpfr number to a string")

         # t contains just digits (no sign, decimal point or exponent)

-        if s[0] == '-':

+        if s[0] == c'-':

             sgn = "-"

             t = char_to_str(s + 1)

         else:

diff -up src/sage/structure/sage_object.pyx.orig src/sage/structure/sage_object.pyx

--- src/sage/structure/sage_object.pyx.orig	2020-10-24 11:37:59.000000000 -0600

+++ src/sage/structure/sage_object.pyx	2020-10-30 14:03:09.091891283 -0600

@@ -688,7 +688,7 @@ cdef class SageObject:

             try:

                 s = self._interface_init_(I)

             except Exception:

-                raise NotImplementedError("coercion of object %s to %s not implemented:\n%s\n%s" % (repr(self), I))

+                raise NotImplementedError(f"coercion of object {repr(self)} to {I} not implemented")

         X = I(s)

         if c:

             try:

diff -up src/sage/symbolic/expression.pyx.orig src/sage/symbolic/expression.pyx

--- src/sage/symbolic/expression.pyx.orig	2020-10-30 12:10:19.747169301 -0600

+++ src/sage/symbolic/expression.pyx	2020-10-30 14:03:09.095891276 -0600

@@ -13071,7 +13071,7 @@ cdef class hold_class:

             sage: SR(2)^5

             32

         """

-        g_set_state('hold', True)

+        g_set_state(b'hold', True)

     def __exit__(self, *args):

         """

@@ -13084,7 +13084,7 @@ cdef class hold_class:

             sage: SR(2)^5

             32

         """

-        g_set_state('hold', False)

+        g_set_state(b'hold', False)

     def start(self):

         """