The previous version used an incorrect /dir1/dir2 pattern to match the
content of dir2. The correct pattern should be /dir1/dir2/ (with the
trailing slash). This commit fixes these patterns.
Regarding codeowners.py:
'git ls-files' can not be used to correctly implement the logic of
CODEOWNERS file patterns, since it doesn't distinguish between
/path/* and /path/. The former pattern in CODEOWNERS file should only
match the files inside /path/, while the latter also matches files in
nested directories.
Because of this, the logic for evaluating patterns is re-implemented,
by converting CODEOWNERS patterns into regular expressions.
Gitlab CODEOWNERS parsing code was used as a reference, in addition to
the approach for converting glob patterns into regular expressions
proposed in https://stackoverflow.com/a/29354254.
