Failure on unhashable functions in Python 2

[mrocklin]

This showed up in Dask's test suite after the recent release. Python 2 only.

In [1]: d = {'a': 1}

In [2]: import cloudpickle

In [3]: cloudpickle.dumps(d.get)
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-3-8adaadeed8cc> in <module>()
----> 1 cloudpickle.dumps(d.get)

/home/mrocklin/Software/anaconda/envs/27/lib/python2.7/site-packages/cloudpickle/cloudpickle.pyc in dumps(obj, protocol)
 844 try:
 845 cp = CloudPickler(file,protocol)
--> 846 cp.dump(obj)
 847 return file.getvalue()
 848 finally:

/home/mrocklin/Software/anaconda/envs/27/lib/python2.7/site-packages/cloudpickle/cloudpickle.pyc in dump(self, obj)
 258 self.inject_addons()
 259 try:
--> 260 return Pickler.dump(self, obj)
 261 except RuntimeError as e:
 262 if 'recursion' in e.args[0]:

/home/mrocklin/Software/anaconda/envs/27/lib/python2.7/pickle.pyc 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 

/home/mrocklin/Software/anaconda/envs/27/lib/python2.7/pickle.pyc 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/mrocklin/Software/anaconda/envs/27/lib/python2.7/site-packages/cloudpickle/cloudpickle.pyc in save_builtin_function(self, obj)
 611 if obj.__module__ == "__builtin__":
 612 return self.save_global(obj)
--> 613 return self.save_function(obj)
 614 dispatch[types.BuiltinFunctionType] = save_builtin_function
 615 

/home/mrocklin/Software/anaconda/envs/27/lib/python2.7/site-packages/cloudpickle/cloudpickle.pyc in save_function(self, obj, name)
 330 interactive prompt, etc) and handles the pickling appropriately.
 331 """
--> 332 if obj in _BUILTIN_TYPE_CONSTRUCTORS:
 333 # We keep a special-cased cache of built-in type constructors at
 334 # global scope, because these functions are structured very

TypeError: unhashable type: 'dict'

[ssanderson]

Looks like this was an unintended consequence of #113. Should be fixed in #145.