Fix reviewers sometimes receiving email they shouldn't

Review Request #7663 — Created Sept. 28, 2015 and submitted — Latest diff uploaded

Information

Review Board
release-2.0.x

Reviewers

Previously, the should_send_own_updates code was not implemented
correctly. If a user had that setting set to False and created a
review request that had a target group that contained themselves and
another target user, then reviewing the review request would cause them
to receive e-mail. This issue has been fixed. A unit test has bee
added to ensure this behaviour does not regress.

Ran unit tests.