cloudpickle cannot save bound classmethods for python2.7

[pierreglaser]

In [1]: import cloudpickle
 ...: class A:
 ...: @classmethod
 ...: def f(cls):
 ...: pass
 ...: cloudpickle.dumps(A.f)

gives

---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-1-b09b8cb46375> in <module>()
 4 def f(cls):
 5 pass
----> 6 cloudpickle.dumps(A.f)

/home/pierreglaser/.virtualenvs/py27/local/lib/python2.7/site-packages/cloudpickle/cloudpickle.pyc in dumps(obj, protocol)
 893 try:
 894 cp = CloudPickler(file, protocol=protocol)
--> 895 cp.dump(obj)
 896 return file.getvalue()
 897 finally:

/home/pierreglaser/.virtualenvs/py27/local/lib/python2.7/site-packages/cloudpickle/cloudpickle.pyc in dump(self, obj)
 266 self.inject_addons()
 267 try:
--> 268 return Pickler.dump(self, obj)
 269 except RuntimeError as e:
 270 if 'recursion' in e.args[0]:

/usr/lib/python2.7/pickle.py in dump(self, obj)
 222 if self.proto >= 2:
 223 self.write(PROTO + chr(self.proto))
--> 224 self.save(obj)
 225 self.write(STOP)
 226 

/usr/lib/python2.7/pickle.py in save(self, obj)
 284 f = self.dispatch.get(t)
 285 if f:
--> 286 f(self, obj) # Call unbound method with explicit self
 287 return
 288 

/home/pierreglaser/.virtualenvs/py27/local/lib/python2.7/site-packages/cloudpickle/cloudpickle.pyc in save_instancemethod(self, obj)
 667 self.save_reduce(types.MethodType, (obj.__func__, obj.__self__), obj=obj)
 668 else:
--> 669 self.save_reduce(types.MethodType, (obj.__func__, obj.__self__, obj.__self__.__class__),
 670 obj=obj)
 671 

AttributeError: class A has no attribute '__class__'

This does not seem to be a regression. The bug is present for any version of cloudpickle.

[ogrisel]

As it's a Python 2 only bug I would not make it a high priority bug unless a user encounters it in a real life usage scenario.

[ogrisel]

Hum I wrote the above comment prior to seeing that you already had found a fix for it...