R1:1eca595e4dc4

Fix Change link in Diffusion history

Summary:
And maybe also something else.
And hopefully don't break anything.

Test Plan: /diffusion/X/history/..., click on //Modified//.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1996