Fix sub-second timing comparison error for Devise confirmation period
On databases such as MySQL, it's possible to get into a timing comparison
error if the value of Confirmable#confirmation_sent_at
is within a second
of 0.days.ago
. This is possible mostly in specs that test this behavior
and most likely not happening in practice. The result of this error causes
a user to be deemed active when it should be inactive. To prevent this
error, we explicitly check the configuration setting to be 0.days.ago
.
Corresponding CE MR: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/11156
Closes #2362 (closed)