R1:b656c87e3756

horribly fix plain-text email for modular transactions

Summary:
This is the quickest and dirtiest fix I could come up with.

`PhabricatorApplicationTransaction::getTitleForMail()` is using `clone $this`, which doesn't actually effect `implementation`.
Ref T9789.

Test Plan: update paste comment, get plaintext mail.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley

Maniphest Tasks: T9789

Differential Revision: https://secure.phabricator.