Save disk space

Summary: so many bytes saved

Test Plan:
http://local.aphront.com:8080/maniphest/view/custom/?tasks=12,14
http://local.aphront.com:8080/maniphest/view/custom/?tasks=~

Reviewers: vrana

Reviewed By: vrana

CC: aran, AnhNhan

Differential Revision: https://secure.phabricator.com/D5211