commit fd1c24518be99e3e2d0891bf7d2c94fbd4d39367
author Jeffrey Yasskin <jyasskin@gmail.com> Mon Jan 07 06:09:40 2008 +0000
committer Jeffrey Yasskin <jyasskin@gmail.com> Mon Jan 07 06:09:40 2008 +0000
tree ae5a461b96e832a20a548ba62a993876b62637be
parent 1db6f80cd5259841f1387f14bf773ebc3c946502

Fix issue 1747: allow classic classes to be checked for being subclasses of
ABCs.

Lib/abc.py

diff --git a/Lib/abc.py b/Lib/abc.py
index 6857029..1ce38a8 100644
--- a/Lib/abc.py
+++ b/Lib/abc.py
@@ -188,7 +188,7 @@
                 cls._abc_negative_cache.add(subclass)
             return ok
         # Check if it's a direct subclass
-        if cls in subclass.__mro__:
+        if cls in getattr(subclass, '__mro__', ()):
             cls._abc_cache.add(subclass)
             return True
         # Check if it's a subclass of a registered class (recursive)