Subscriber user shouldn't get mail notification about editing CR comments

Pre-conditions:
Two users are registered (User1, User2). At least one has real e-mail (User1).
User1 subscribe to a CR. Sign in as User2.

Steps to reproduce:
1. User2 leave a comment in the CR
2. User2 edit this comment.
3. Check e-mail of the User1.

Actual result: User1 has 2 new message from jtalks@inbox.ru first message with notification of leaving comment by User2 and second - with notification of editing this message by User2)

Expected result: User1 has 1 new message from jtalks@inbox.ru (message with notification of leaving comment by User2)