diff -r 0f82b29f7494 -r c5bcd946a34b mercurial/localrepo.py
--- a/mercurial/localrepo.py	Wed Nov 13 22:40:32 2019 +0100
+++ b/mercurial/localrepo.py	Tue Nov 19 11:59:43 2019 +0100
@@ -1568,7 +1568,7 @@
             else:
                 raise error.ProgrammingError(
                     b"unsupported changeid '%s' of type %s"
-                    % (changeid, pycompat.sysstr(type(changeid)))
+                    % (changeid, pycompat.bytestr(type(changeid)))
                 )
 
             return context.changectx(self, rev, node)