This is a quick fix by only append match line once
when calling diff_lines_for_serializer multiple time.

Also enable feature by default

Docs: Add automatic redirects to many moved files

See merge request gitlab-org/gitlab-ce!25902

Docs: Fix markdown for link in chatops doc

See merge request gitlab-org/gitlab-ce!25952

Add infos about runners concurrent jobs in .gitlab-ci.yml documentation

See merge request gitlab-org/gitlab-ce!25809

Docs: Fix CI/CD related anchors

See merge request gitlab-org/gitlab-ce!25591

Docs: Clarify how Auto DevOps deploys using deploy token

See merge request gitlab-org/gitlab-ce!25787

We were emphasising a point that's no longer true since we implemented
deploy tokens in 11.0 so rationalize the docs here.

Update pipeline webhook example response

Closes #53121

See merge request gitlab-org/gitlab-ce!25914

Remove confusing author name from Changelog docs

See merge request gitlab-org/gitlab-ce!25928

Fix the last-ditch memory killer pgroup SIGKILL

See merge request gitlab-org/gitlab-ce!25940

Update cleanup.rake to fix a typo in the error message

See merge request gitlab-org/gitlab-ce!25901

Filter merge requests by target branch

See merge request gitlab-org/gitlab-ce!24380

Align EmailValidator to validate_email gem implementation.

Closes #57352

See merge request gitlab-org/gitlab-ce!24971

Remove select2-rails (select2 is now installed via yarn)

See merge request gitlab-org/gitlab-ce!25929

Docs: intro to CI/CD - fix typos

See merge request gitlab-org/gitlab-ce!25917

Skip gitlab:ui:visual job for docs again

See merge request gitlab-org/gitlab-ce!25922

Revert "Merge branch 'remove-select2-rails' into 'master'"

See merge request gitlab-org/gitlab-ce!25920

Fix gl-loading-icon bug before gitlab-ui update

See merge request gitlab-org/gitlab-ce!25683

This reverts merge request !17871

Fixed sticky bar styling in Safari

Closes #58625

See merge request gitlab-org/gitlab-ce!25913

In the example response we have builds with status `success` but the
property `runner` is null, which is not a realistic representation of
the response. The runner is always sent if the build has ran.

closes https://gitlab.com/gitlab-org/gitlab-ce/issues/53121

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/58625

Externalize admin deploy keys strings

See merge request gitlab-org/gitlab-ce!24712

CE FE Refactor dashboard gold trial callouts

See merge request gitlab-org/gitlab-ce!25483

Disallow reopening of locked merge request

Closes #56864

See merge request gitlab-org/gitlab-ce!24882

Fixes #56864

Remove unnecessary license check in operations controller

See merge request gitlab-org/gitlab-ce!25728

Resolve "Project template for Android"

Closes #58649

See merge request gitlab-org/gitlab-ce!25870