Summary:
Hopefully this would rule out things like double blank lines and
inconsistent commit title.
Test Plan: `arc unit`
Reviewers: #sourcecontrol, simonfar
Reviewed By: simonfar
Subscribers: mjpieters
Differential Revision: https://phabricator.intern.facebook.com/D4036978
Signature: t1:4036978:1476807264:414cd17672f59675be104c0026a8e50efac8b15d