Summary: See <https://discourse.phabricator-community.org/t/exception-when-viewing-previous-revision-from-blame/2454/2>. Test Plan: Viewed blame, clicked "Skip Past This Commit". Got jumped to the right place instead of a URI exception. Reviewers: amckinley Reviewed By: amckinley Differential Revision: https://secure.phabricator.com/D20222