Remove references to pylint E8712

E8712 is not a thing, at least not according to pylint's docs:

http://docs.pylint.org/search.html?q=E8712

Also, a couple other fixes:

1. Double quotes to single quotes to follow style conventions
2. "is Bool", not "== Bool".
Merge pull request #13466 from terminalmage/lint

Remove references to pylint E8712