diff -r c093cc6e6c99 -r 313e3a279828 mercurial/extensions.py
--- a/mercurial/extensions.py	Thu Nov 07 03:59:22 2019 -0800
+++ b/mercurial/extensions.py	Thu Nov 07 13:18:19 2019 -0500
@@ -591,9 +591,7 @@
             break
 
     if currcls is object:
-        raise AttributeError(
-            r"type '%s' has no property '%s'" % (cls, propname)
-        )
+        raise AttributeError("type '%s' has no property '%s'" % (cls, propname))
 
 
 class wrappedfunction(object):