COMPAT: if docstring_wrapper is activated on a class, don't fail

Author: jreback

pandas/util/decorators.py

@@ -261,6 +261,11 @@ def __init__(self, func, creator, default=None):
                          if hasattr(func, attr)])
 
     def __get__(self, instance, cls=None):
+
+        # we are called with a class
+        if instance is None:
+            return self
+
         # we want to return the actual passed instance
         return types.MethodType(self, instance)