Migrations shouldn't fail RuboCop checks - especially lint checks, such
as the nested method check. To avoid changing code in existing
migrations, add the magic comment to the top of each of them to skip
that file.
On GitLab.com, there are 1560 project notification settings with no valid project
all created on 2016-04-15 10:38:53 for some reason. This migration should purge
those entries.
b8f38437 should prevent this issue from occurring in the first place.
Closesgitlab-com/support-forum#678