Inconsistent dumps of function in different contexts

Pickling a function in the REPL and from the command line gives different results, it looks like the closure is not included in the REPL version. This results in problems, for example, when unpickling on remote workers such as dask.

```
$ cat cloudpickle_example.py
import cloudpickle
def some_function(a, b=1):
""" things """
return a, b

if __name__ == '__main__':
print(cloudpickle.dumps(some_function))
$ python cloudpickle_example.py
b'\x80\x04\x954\x01\x00\x00\x00\x00\x00\x00\x8c\x17cloudpickle.cloudpickle\x94\x8c\x0e_fill_function\x94\x93\x94(h\x00\x8c\x0f_make_skel_func\x94\x93\x94h\x00\x8c\r_builtin_type\x94\x93\x94\x8c\x08CodeType\x94\x85\x94R\x94(K\x02K\x00K\x02K\x02KCC\x08|\x00|\x01f\x02S\x00\x94\x8c\x08 things \x94\x85\x94)\x8c\x01a\x94\x8c\x01b\x94\x86\x94\x8c\x16cloudpickle_example.py\x94\x8c\rsome_function\x94K\x02C\x02\x00\x02\x94))t\x94R\x94J\xff\xff\xff\xff}\x94\x87\x94R\x94}\x94(\x8c\x07globals\x94}\x94\x8c\x08defaults\x94K\x01\x85\x94\x8c\x04dict\x94}\x94\x8c\x06module\x94\x8c\x08__main__\x94\x8c\x0eclosure_values\x94N\x8c\x08qualname\x94h\x11utR.'
$ ipython
Python 3.6.4 |Anaconda, Inc.| (default, Mar 12 2018, 20:05:31)
Type 'copyright', 'credits' or 'license' for more information
IPython 6.2.1 -- An enhanced Interactive Python. Type '?' for help.

In [1]: import cloudpickle_example as c; import cloudpickle

In [2]: cloudpickle.dumps(c.some_function)
Out[2]: b'\x80\x04\x95)\x00\x00\x00\x00\x00\x00\x00\x8c\x13cloudpickle_example\x94\x8c\rsome_function\x94\x93\x94.'
```