The pip-specific Path implementation has been removed, and all its
usages replaced by pathlib.Path. The tmpdir and tmpdir_factory fixtures
are also removed, and all usages are replaced by tmp_path and
tmp_path_factory, which use pathlib.Path.
The pip() function now also accepts pathlib.Path so we don't need to put
str() everywhere. Path arguments are coerced with os.fspath() into str.
The html5lib library isn't strictly required as the same functionality
can be achieved through the stdlib html.parser module.
The html5lib is one of the largest uses of the six library. By dropping
this unnecessary dependency, the pip project is closer to dropping the
six library.
Additionally, html5lib maintenance has slowed down and the project has
rejected pull requests to drop Python 2 support.
For now, the html5lib code remains, but is gated behind a command
line option: `--use-deprecated=html5lib`. After a sufficient amount of
time has passed without any reported bugs, the vendored library and this
flag can be removed completely.
adds VERBOSE custom log level between DEBUG and INFO
used when `-v` is given. Now require -vv to enable full debug output.
Messages can be logged with VERBOSE level to promote them to `-v` output instead of `-vv`
