@gvanrossum This fixes the red master (something changed in Travis environment). The fix also discovered that flake8 was not run for long time, so I also fix it.

Could you please take a look?

Whats the #noqa tag actually doing?

That's indicating to linters (e.g. flake8, pylint) that they should not complain about that line. There are several tests that intentionally put bad code in a string type annotation or in a type comment (to verify that the typing module handles these correctly), and some linters are smart enough to look inside type comments or string annotations and complain, making the build fail. So the # noqa shuts up the linter and so the build passes.