Prevent Differential changeset HTML anchors from colliding with comment anchors
Summary:
Fixes T12970. This is easier than I expected, and appears to occur in only one place.
This prevents a change from ever generating with an anchor like `#12345678`, which is ambiguous because it may be a comment anchor.
Test Plan: Viewed a revision, saw new `change-xxxyyyzzz` anchors, clicked one, got jumped to the right place.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T12970
Differential Revision: https://secure.phabricator.com/D18465