Summary: Useful in cases where there is an Arcanist Project but not a repository tracked by Phabricator for a particular revision.
Test Plan: Created a new rule to flag Differential revisions with a particular Arcanist project, verified that it applied as expected via the test console to revisions with the project specified and with a different project specified.
Reviewers: #blessed_reviewers, epriestley
Reviewed By: #blessed_reviewers, epriestley
Subscribers: aran, epriestley, Korvin
Differential Revision: https://secure.phabricator.com/D8463
8818252f52