Fix error rendering submodules in MR diffs when there is no .gitmodules

See merge request gitlab-org/gitlab-ce!31162

Prefer `flat_map` over `map` + `flatten`

See merge request gitlab-org/gitlab-ce!31144

Convert several occurrences of `map` + `flatten` to
`flat_map` where applicable.

Without this change, we get a NoMethodError on nil

Add development documentation on label filtering

Closes #49651

See merge request gitlab-org/gitlab-ce!30741

Update dependency @gitlab/ui to ^5.9.0

See merge request gitlab-org/gitlab-ce!31153

The GitLab UI update changed the spinner selector from `spinner` to
`gl-spinner`, so we need to update it, so that our tests won't fail.

Extract Auto DevOps deploy functions in a base image

Closes #50286

See merge request gitlab-org/gitlab-ce!30404

Adds event enum column to DesignsVersions join table

See merge request gitlab-org/gitlab-ce!30745

Support indentation in the markdown editor

Closes #25070

See merge request gitlab-org/gitlab-ce!28914

It will be hooked up to the markdown editor later

Ensure Warden triggers after_authentication callback

See merge request gitlab-org/gitlab-ce!31138

By not triggering the callback:
- ActiveSession lookup keys are not cleaned
- Devise also misses its hook related to session cleanup

CE port of "Stablize editing scope label spec - retry if dropdown is not visible"

See merge request gitlab-org/gitlab-ce!31145

Respect alt email when sending group access notifications

See merge request gitlab-org/gitlab-ce!31089

When sending access granted/rejected emails we should also respect
custom emails set for groups/sub-groups

Feature test for gfm embedding metrics

See merge request gitlab-org/gitlab-ce!30621

Add points how to prepare for database reviews

Closes #65126

See merge request gitlab-org/gitlab-ce!31158

CI Docs update for Marketing

See merge request gitlab-org/gitlab-ce!30440

Update README.md - add CTA to watch Mastering CI/CD webcast and 5 teams that made the switch to GitLab CI/CD article

Add docs for template field in prometheus alerts

See merge request gitlab-org/gitlab-ce!30900

Add Troubleshooting section for Merge Train documentation

Closes #64948

See merge request gitlab-org/gitlab-ce!31033

Add trouble shooting sections

Update links to relative

Closes #61945

See merge request gitlab-org/gitlab-ce!31084

Following the single docs codebase change, all internal links
should be relative. Also cleans up one table

Resolve "Incorrect message interpolation on project listing"

Closes #65088

See merge request gitlab-org/gitlab-ce!31121

Logging sidekiq worker class name in SidekiqMemoryKiller

See merge request gitlab-org/gitlab-ce!30996

Fix outbound_local_requests_whitelist nil for existing ApplicationSetting records

Closes #65096

See merge request gitlab-org/gitlab-ce!31123

It needs to default to an empty array logically.

Add doc about incident issue labels

See merge request gitlab-org/gitlab-ce!31107

Add namespace label toggle

See merge request gitlab-org/gitlab-ce!30935

Added the ability to update the namespace label text for gitlab-managed

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/65126.

Came up in the database office hours call on 2019-07-25.

Add frozen_string_literal to spec/support

See merge request gitlab-org/gitlab-ce!31132

Remove \ from unicorn\_stderr.log

See merge request gitlab-org/gitlab-ce!31159