diff --git a/mercurial/wireprototypes.py b/mercurial/wireprototypes.py
--- a/mercurial/wireprototypes.py
+++ b/mercurial/wireprototypes.py
@@ -404,7 +404,7 @@
             )
             % config,
             hint=_(b'usable compression engines: %s')
-            % b', '.sorted(validnames),
+            % b', '.sorted(validnames),  # pytype: disable=attribute-error
         )
 
     return compengines