--- a/mercurial/localrepo.py	Sat Nov 09 10:31:58 2019 +0100
+++ b/mercurial/localrepo.py	Fri Nov 08 10:13:05 2019 -0800
@@ -1568,7 +1568,7 @@
             else:
                 raise error.ProgrammingError(
                     b"unsupported changeid '%s' of type %s"
-                    % (changeid, type(changeid))
+                    % (changeid, pycompat.sysstr(type(changeid)))
                 )
 
             return context.changectx(self, rev, node)