Warning not filtered as supposed to

[cblegare]

The warning emitted for missing standard script name in py36compat.py is not suppressed by manifest_maker.warn but seems to be supposed to.

I found this while exploring a setup.py as a directory containing a __main__.py. I happened to run

python setup.py/__main__.py

and I had a warning about the file __main__.py missing.

You can suppress the warning by using the script_name keyword argument of setuptools.setup like so:

from setuptools import setup

setup(
    name="mypackage",
    # ... a plethora of other kwargs
    script_name="setup.py"
)

[jaraco]

Seems reasonable. Can you send a pull request?