Summary:
This command will allow us to expose simple api to all automation checking
working copy parent. It's meant to be overridden by our wrapper to read the
dirsate directly without shelling out to hg (see D4454504 )
Test Plan: see tests
Reviewers: #mercurial, durham, rmcelroy
Reviewed By: rmcelroy
Subscribers: mjpieters
Differential Revision: https://phabricator.intern.facebook.com/D4454502
Signature: t1:4454502:1485441135:09902c6437a7af55dfa5c97e3165681de687231f
