try to normalize order between py 2 and 3 by ignoring object in the MRO

src/zope/testrunner/runner.py

@@ -887,7 +887,7 @@ def order_by_bases(layers):
     getmro = inspect.getmro
 
     def layer_sortkey(layer):
-        return tuple((c.__module__, c.__name__) for c in getmro(layer)[::-1])
+        return tuple((c.__module__, c.__name__) for c in getmro(layer)[::-1] if c is not object)
 
     layers = [layer for layer in layers]
     layers.sort(key=layer_sortkey, reverse=True)