Don't create mentions for dependent diffs


Don't create mentions for dependent diffs

Fixes T6858. We shouldn't create mentions for dependent diffs.

NOTE: This won't fix the issue for existing revisions (which have the mentions edge), but I think that this is harmless.

Test Plan: Added Depends on Dxxx to a differential summary. Saw a josh added a dependent revision transaction, but no explicit mention.

Reviewers: Blessed Reviewers, epriestley

Reviewed By: Blessed Reviewers, epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T6858

Differential Revision: https://secure.phabricator.com/D11460