Comment 2 for bug 1502105

Fixed in https://github.com/ubuntu-core/snapcraft/pull/50

I confirmed that without the snap_fileset of the python plugins I get:
"Error: parts py1 and py2 have the following file paths in common which have different contents:"

This is missing a regression test.
I'm proposing this one: https://github.com/ubuntu-core/snapcraft/pull/109

For next branches, please don't bundle multiple bug fixes in the same pull request. It makes really hard to see where is the fix.