setup: try a non-pure version of the local Mercurial if the pure fails
Things like `zstd` can make the pure version fails.
# Declare Windows-specific requirements for generating
# the compiled (frozen) set of requirements in
# ./requirements-windows-py3.txt.
# If run on Windows, it may be necessary to run dos2unix
# on the output file to replace any CRLF newlines with LF.
docutils
dulwich
# Needed by the release note tooling
fuzzywuzzy
keyring
pygit2
pygments
# Needed by the phabricator tests
pytest-vcr
# Need to list explicitly so dependency gets pulled in when
# not running on Windows.
pywin32-ctypes
windows-curses