Fix project default branch change

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Add useless test. Uncomment when we improve testing

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'fix-default-branch' into 'master'

Fix project default branch change

It is a regression since 7.0. It was caused with switch to `strong_params`.

This MR is safe to merge and it fixes issue https://gitlab.com/gitlab-org/gitlab-ce/issues/433

See merge request !984