R1:81e2a1cf6b22

Always parse the first line of a commit message as a title

Summary: Fixes T10312. If your first line is "Reviewers: xyz", it's a title, not a "Reviewers" field.

Test Plan: Added unit test.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10312

Differential Revision: https://secure.phabricator.com/D17122