Instead of running ClosingIssueExtractor for every commit in a merge
request we can gather all the commit messages (and the merge request
description), concatenate all this together and then run
ClosingIssueExtractor only once.

The result of this is that MergeRequest#closes_issues is now between
3.5x and 4x faster than the old setup. Using a merge request with 10
commits (each referencing a number of issues to close) this reduced the
call duration from around 200 milliseconds to around 50 milliseconds.

As a result of these changes the Jira related tests for
MergeRequest#closes_issues have been removed. These tests stubbed
Commit#closes_issues meaning that the only code that was really tested
was the call to Array#uniq to filter out duplicate issues. As this code
is no longer used (nor present) the corresponding tests were removed.

Related: gitlab-org/gitlab-ce#12419

[ci skip]

[ci skip]

Update Ruby version to 2.2.4 (latest previous stable) and update docs

Tests and issues added to https://github.com/gitlabhq/gitlabhq/issues/8696 were all fine after the upgrade. 

Main issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/3340

See merge request !2534

Improve performance of retrieving last update times for events

See 75195eefcca4cb3961986c90c8e837da02f30134 and
https://gitlab.com/gitlab-org/gitlab-ce/issues/12415#note_3387317
for the juicy details.

Related issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/12415

See merge request !2613

Skip the 2FA requirement during logout

See merge request !2581

[ci skip]

Increase contrast between highlighted code comments and inline diff marker.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/12737.

It was especially bad in Monokai, better now.

See merge request !2629

Fix CI runner version not being properly updated when asked for a build

Due to broken implementation of attribute_for_keys the runner information was not updated correctly.

This MR adds test to check that such scenario will never happen again.

See merge request !2618

Return a 404 instead of a 500 when accessing a non-existent group

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/3352

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/5600

See merge request !2614

Limit jquery-ui requires to what we actually use



See merge request !2274

Update wording for 2FA requirement notice



See merge request !2582

Remove link from system hook

Closes #12672

See merge request !2588

Bump octokit to `~> 3.8.0`

Closes #2877

See merge request !2536

Fix hot reloading for CI API



See merge request !2617

Due to broken implementation of attribute_for_keys the runner information was not updated correctly.

This MR adds test to check that such scenario will never happen again.

Refactor forking workflow documentation

Closes #5974 

See merge request !2623

[ci skip]

By simply loading the first event from the already sorted set we save
ourselves extra (slow) queries just to get the latest update timestamp.
This removes the need for Event.latest_update_time and significantly
reduces the time needed to build an Atom feed.

Fixes gitlab-org/gitlab-ce#12415

Use generic method to checks if artifacts are available

Closes #12626

See merge request !2576

Fix typo on artifacts doc



See merge request !2622

[ci skip]

[ci skip]

Update ExternalIssue regex for JIRA integration

The pattern in the `::reference_pattern` class method in the
`ExternalIssue` model does not match all valid forms of JIRA project
names. I have updated the regex to match JIRA project names with numbers
and underscores. More information on valid JIRA project names can be
found here:
https://confluence.atlassian.com/jira/changing-the-project-key-format-192534.html

* The first character must be a letter,
* All letters used in the project key must be from the Modern Roman Alphabet and upper case, and
* Only letters, numbers or the underscore character can be used.

See merge request !2598

The pattern in the `::reference_pattern` class method in the
ExternalIssue model does not match all valid forms of JIRA project
names. I have updated the regex to match JIRA project names with numbers
and underscores. More information on valid JIRA project names can be
found here:
https://confluence.atlassian.com/jira/changing-the-project-key-format-192534.html

* The first character must be a letter,
* All letters used in the project key must be from the Modern Roman Alphabet and upper case, and
* Only letters, numbers or the underscore character can be used.

Bug/jschatz1/file browser lines

Fixes #12725 

![Screen_Shot_2016-01-26_at_11.19.39_AM](/uploads/c5f5a143926600e02de4cfc0687ed8dd/Screen_Shot_2016-01-26_at_11.19.39_AM.png)


See merge request !2615

Bump Workhorse version to 0.6.2

Fix for #12634 has been introduced in gitlab-org/gitlab-workhorse!34.

See merge request !2616

Merge branch 'search-box-in-group-members-view-is-too-small-for-placeholder-in-chrome' into 'master'

Fixes: Search box in Group Members view is too small for placeholder in Chrome

Fixes #2498 

![Screen_Shot_2016-01-25_at_11.55.57_PM](/uploads/de4fda98cd8552641208b3a7a9277e35/Screen_Shot_2016-01-25_at_11.55.57_PM.png)


See merge request !2609