TypeError when calling a pickled + unpickled function in __main__ with keyword-only argument

[lesteve]

import cloudpickle

def func_with_kw_only_args(a, *, b=1):
    return a + b


new_func = cloudpickle.loads(cloudpickle.dumps(func_with_kw_only_args))
new_func(1)

Error:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-18-ee6063f05eec> in <module>
      6 
      7 new_func = cloudpickle.loads(cloudpickle.dumps(func_with_kw_only_args))
----> 8 new_func(1)
      9 
     10 

TypeError: func_with_kw_only_args() missing 1 required keyword-only argument: 'b'

Original bug was seen in joblib: joblib/joblib#863

Note: there is no error when putting the function with keyword-only arguments in a Python module.

[pierreglaser]

Yeah, apparently we forget to write the __kwdefaults__ attribute to func_with_kw_only_args's pickle. We just pass __defaults__, which seems to suffice except in the keyword-only argument case.