diff -up src/sage/doctest/control.py.orig src/sage/doctest/control.py
--- src/sage/doctest/control.py.orig	2020-10-24 11:37:59.000000000 -0600
+++ src/sage/doctest/control.py	2020-10-30 13:55:37.330649309 -0600
@@ -115,7 +115,6 @@ class DocTestDefaults(SageObject):
         self.valgrind = False
         self.massif = False
         self.cachegrind = False
-        self.omega = False
         self.failed = False
         self.new = False
         self.show_skipped = False
@@ -318,7 +317,7 @@ class DocTestController(SageObject):
             if options.gdb or options.debug:
                 # Interactive debuggers: "infinite" timeout
                 options.timeout = 0
-            elif options.valgrind or options.massif or options.cachegrind or options.omega:
+            elif options.valgrind or options.massif or options.cachegrind:
                 # Non-interactive debuggers: 48 hours
                 options.timeout = int(os.getenv('SAGE_TIMEOUT_VALGRIND', 48 * 60 * 60))
             elif options.long:
@@ -1109,13 +1108,8 @@ class DocTestController(SageObject):
             elif opt.cachegrind:
                 toolname = "cachegrind"
                 flags = os.getenv("SAGE_CACHEGRIND_FLAGS", "")
-            elif opt.omega:
-                toolname = "exp-omega"
-                flags = os.getenv("SAGE_OMEGA_FLAGS", "")
             cmd = "exec valgrind --tool=%s "%(toolname)
             flags += ''' --log-file="%s" ''' % logfile
-            if opt.omega:
-                toolname = "omega"
             if "%s" in flags:
                 flags %= toolname + ".%p" # replace %s with toolname
         cmd += flags + sage_cmd
@@ -1201,10 +1195,10 @@ class DocTestController(SageObject):
 
         """
         opt = self.options
-        L = (opt.gdb, opt.valgrind, opt.massif, opt.cachegrind, opt.omega)
+        L = (opt.gdb, opt.valgrind, opt.massif, opt.cachegrind)
         if any(L):
             if L.count(True) > 1:
-                self.log("You may only specify one of gdb, valgrind/memcheck, massif, cachegrind, omega")
+                self.log("You may only specify one of gdb, valgrind/memcheck, massif, cachegrind")
                 return 2
             return self.run_val_gdb()
         else:
diff -up src/sage/interfaces/singular.py.orig src/sage/interfaces/singular.py
--- src/sage/interfaces/singular.py.orig	2020-10-24 11:37:59.000000000 -0600
+++ src/sage/interfaces/singular.py	2020-10-30 13:55:37.332649306 -0600
@@ -2349,7 +2349,7 @@ def generate_docstring_dictionary():
     nodes.clear()
     node_names.clear()
 
-    singular_docdir = SINGULARPATH + "/../info/"
+    singular_docdir = "/usr/share/info/"
 
     new_node = re.compile(r"File: singular\.hlp,  Node: ([^,]*),.*")
     new_lookup = re.compile(r"\* ([^:]*):*([^.]*)\..*")
@@ -2357,8 +2357,9 @@ def generate_docstring_dictionary():
     L, in_node, curr_node = [], False, None
 
     # singular.hlp contains a few iso-5559-1 encoded special characters
-    with io.open(os.path.join(singular_docdir, 'singular.hlp'),
-                 encoding='latin-1') as f:
+    import gzip
+    with gzip.open(os.path.join(singular_docdir, 'singular.hlp.gz'),
+                   encoding='utf-8') as f:
         for line in f:
             m = re.match(new_node,line)
             if m:
diff -up src/sage_setup/docbuild/ext/multidocs.py.orig src/sage_setup/docbuild/ext/multidocs.py
--- src/sage_setup/docbuild/ext/multidocs.py.orig	2020-10-24 11:37:59.000000000 -0600
+++ src/sage_setup/docbuild/ext/multidocs.py	2020-10-30 13:55:37.332649306 -0600
@@ -82,8 +82,11 @@ def merge_environment(app, env):
             for ind in newalldoc:
                 # treat subdocument source as orphaned file and don't complain
                 md = env.metadata.get(ind, dict())
-                md['orphan'] = 1
-                env.metadata[ind] = md
+                try:
+                    md['orphan'] = 1
+                    env.metadata[ind] = md
+                except AttributeError:
+                    env.metadata[ind] = {'orphan'}
             # merge the citations
             newcite = {}
             for ind, (path, tag, lineno) in citations.items():