diff -U3 -r mercurial-5.4-orig/hgdemandimport/__init__.py mercurial-5.4/hgdemandimport/__init__.py
--- mercurial-5.4-orig/hgdemandimport/__init__.py	2020-05-01 18:17:29.000000000 +0200
+++ mercurial-5.4/hgdemandimport/__init__.py	2020-09-01 18:04:40.540165952 +0200
@@ -56,6 +56,7 @@
     '__builtin__',
     'builtins',
     'urwid.command_map',  # for pudb
+    '_ast', # https://bugzilla.redhat.com/show_bug.cgi?id=1871992
 }
 
 _pypy = '__pypy__' in sys.builtin_module_names