You're welcome. And to confirm a bit that the borked setuptools is not from the python36 AUR package, I find:

$ python3.6
Python 3.6.6 (default, Aug 17 2018, 18:08:24) 
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pkg_resources
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'pkg_resources'
>>>

And that's pristine:

$ yaourt -Qo /usr/lib/python3.6
/usr/lib/python3.6/ is owned by python36 3.6.6-1