Log Message:
Updated py-mercurial to 4.1.2.

Mercurial 4.1.2 (2017-4-3)

This is a regularly-scheduled bugfix release.

    Mercurial should work inside IIS on Windows again. (issue5493)

    zstd support now refuses to work on old bundle formats. (issue5506)

    Merges involving subrepositories no longer crash in some cases. (issue5505)

    Checking for new heads during push is no longer accidentally quadratic