Closes#1077.
There were two issues:
- Paths for coverage.py suddenly were absolute instead of relative, so we strip
the common base part if that happens.
/home/florian/proj/qutebrowser/git/qutebrowser/browser/cookies.py has 100%
coverage but is not in perfect_files!
/home/florian/proj/qutebrowser/git/qutebrowser/browser/http.py has 100%
coverage but is not in perfect_files!
[...]
- There was an io.UnsupportedOperationError in test_check_coverage.py because
of pytest-faulthandler, so we just don't load that in the subprocess.