Fixed localcommits include on getDiffDict
Summary: Ref T10808
Test Plan: Call differential.querydiffs method and expect 'local:commits' property be added to the result.
Reviewers: epriestley, Blessed Reviewers
Reviewed By: epriestley, Blessed Reviewers
Subscribers: Korvin
Maniphest Tasks: T10808
Differential Revision: https://secure.phabricator.com/D15710