contrib/packaging/requirements_win32.txt.in

merge: introduce a revert_to() for that use-case

In the same vein as the previous patch.

Differential Revision: https://phab.mercurial-scm.org/D7901

docutils
dulwich
keyring
pygments
# Need to list explicitly so dependency gets pulled in when
# not running on Windows.
pywin32-ctypes