Prevent a 500 when a repository's root_ref is nil

Closes #14259

See merge request !3278

Improved issue sidebar

Updated the spacing throughout the sidebar so that it fits better on smaller screens. Also adds a more participants button to show any other participants after the first row.

Closes #13353

See merge request !3097

Dashboard labels

Previously because there were no JSON endpoint for labels or milestones
it was fetching HTML and parsing that. This is wrong.

It now fetches from a JSON endpoint.

This also fixes the dashboard/issues page not loading labels or
milestones as the path used to be only for a single project. So instead
I have created a endpoint for labels & milestones JSON on dashboard.

See merge request !3253

Fixes issue with close button not working on MR

Closes #14383

See merge request !3295

Add note in upgrade guide to choose the correct version tag

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/3448

@rspeicher I'm assigning to you since as a release manager you should know better. Let's keep it in this guide for now and then start copying it in the future ones.

See merge request !2284

Show a notice for diffs that are empty/too large

This builds upon https://gitlab.com/gitlab-org/gitlab_git/merge_requests/72 but will fail until said MR has been merged.

Fixes gitlab-org/gitlab-ce#13912, gitlab-org/gitlab-ce#13644, gitlab-org/gitlab-ce#13557, gitlab-org/gitlab-ce#13267, gitlab-org/gitlab-ce#3906

See merge request !3185

[ci skip]

Add side padding to content-list if inside panel
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Fixes #14367, #14349

See merge request !3273

Use relative links in `doc`, fix broken generated HTML links

Links like (doc/web_hooks/web_hooks.md) work in the GitLab source code
web interface, but the HTML generator produces broken links in the `doc`
subdirectories:  
http://doc.gitlab.com/ce/hooks/doc/web_hooks/web_hooks.html  
instead of the right one  
http://doc.gitlab.com/ce/web_hooks/web_hooks.html  
in  
http://doc.gitlab.com/ce/hooks/custom_hooks.html.

Fixes #14338 


See merge request !3261

Remove CI duplication.



See merge request !3290

Improve award emoji test reliability by checking that the emoji is displayed before the search field is focused

See merge request !3288

Check push permissions only when pushing directly to target branch.

Fixes #14374 

See merge request !3280

Fix bug causing dropdown to get cut off in project page

closes #14336 

### Before
![Screen_Shot_2016-03-16_at_11.30.40_PM](/uploads/9f8dd10f0627cdfbd49d7127b233b105/Screen_Shot_2016-03-16_at_11.30.40_PM.png)

![Screen_Shot_2016-03-16_at_11.30.53_PM](/uploads/6dfe64d68867d158a11be7e74cbd1520/Screen_Shot_2016-03-16_at_11.30.53_PM.png)


### After
![Screen_Shot_2016-03-16_at_11.30.14_PM](/uploads/2b87cc17522e8a425a97a78b36982873/Screen_Shot_2016-03-16_at_11.30.14_PM.png)

See merge request !3257

Fix inconsistency in the header of issue and merge request pages

closes #13550 

# For Issue Page

### Before
![Screen_Shot_2016-03-17_at_8.46.59_PM](/uploads/ede7f2b98395362ae87e6258cc10520a/Screen_Shot_2016-03-17_at_8.46.59_PM.png)

### After
![Screen_Shot_2016-03-17_at_8.48.56_PM](/uploads/da7adf17cb397ddc0677a6a5e8033b8e/Screen_Shot_2016-03-17_at_8.48.56_PM.png)

# For Merge request Page

### Before
![Screen_Shot_2016-03-17_at_8.45.45_PM](/uploads/10137827c05c8166a0aa429687e50d1b/Screen_Shot_2016-03-17_at_8.45.45_PM.png)

### After
![Screen_Shot_2016-03-17_at_8.45.01_PM](/uploads/92151c03cfe29b71090a1e0ad31abd6e/Screen_Shot_2016-03-17_at_8.45.01_PM.png)


See merge request !3279

Fixed alignment of download dropdown

With the new dropdown CSS - some dropdowns might look a bit odd

## Previously

![Screen_Shot_2016-03-16_at_11.46.04](/uploads/c1a8fc95ed4410de35d7bd5caedf28f5/Screen_Shot_2016-03-16_at_11.46.04.png)

## Now

![Screen_Shot_2016-03-16_at_11.45.26](/uploads/998637fe0872b2e826a8c17d183499dc/Screen_Shot_2016-03-16_at_11.45.26.png)

See merge request !3245

Fixed filter spacing

Closes #14350

![Screen_Shot_2016-03-17_at_10.21.33](/uploads/5b8f39134cc90ce1dd6565f665a39838/Screen_Shot_2016-03-17_at_10.21.33.png)

See merge request !3267

Bump Git version requirement to 2.7.4

[ci skip]

See merge request !3281

Edited timeago text on comments

Unified the 'edited text' to be the same in descriptions and comments

Closes #5538 

See merge request !3063

Revert color for links inside gray areas

**Before**

![Screen_Shot_2016-03-17_at_12.23.17_PM](/uploads/55e518721d83c3bfc42edba3e97ec44d/Screen_Shot_2016-03-17_at_12.23.17_PM.png)

**After**

![Screen_Shot_2016-03-17_at_12.23.03_PM](/uploads/08fbf8e9139e4eadf191102cffd29617/Screen_Shot_2016-03-17_at_12.23.03_PM.png)

Reverts !3147

See merge request !3276

Hide builds from Project's settings when the feature is disabled

Resolves https://gitlab.com/gitlab-org/gitlab-ce/issues/13944

See merge request !3220

Cache project avatars stored in Git

Related issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/14363

See merge request !3272

The avatar logic has been moved from Project to Repository as this makes
caching easier. The logic itself in turn has been changed so that the
logo file names are cached in Redis. This cache is flushed upon pushing
a commit but _only_ if:

1. The commit was pushed to the default branch
2. The commit actually changes any of the logo files

If no branch or commit is given the cache is flushed anyway, this
ensures that calling Repository#expire_cache without any arguments still
flushes the avatar cache (e.g. this is used when removing a project).

Fixes gitlab-org/gitlab-ce#14363

Pre-selects values on issue and merge request dropdown

Closes #14290

See merge request !3233

Adjusted behavior so canceled builds tagged as allowed to fail do not fail build

## What does this MR do?
This diff changes the 'Allowed to fail' flag to also ignore canceled builds, whereas before, canceled builds could fail the suite even if they were marked as 'Allowed to fail'

dupe of !3258 to force a build

## Are there points in the code the reviewer needs to double check?
no

## Why was this MR needed?
Unexpected behavior as a user

## What are the relevant issue numbers?

## Screenshots (if relevant)
![whatisgoingon](/uploads/fcd7c8f3d8454bc730d7fd41eff59b31/whatisgoingon.png)

See merge request !3271

Merge duplicate cache entry in CI docs



See merge request !3208

PostReceive refactor

Back-ported PostReceive refactor made for https://gitlab.com/gitlab-org/gitlab-ee/issues/367 in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/267

See merge request !3264

External Users

The user has the rights of a public user execpt it can never create a project, group, or team. Also it cant view internal projects.

Partially fix for both #4009 and #13938 (except the LDAP sync or a pattern to detect external users)


![Screen_Shot_2016-03-14_at_22.02.52](/uploads/486a84ab3acb98c6cfb71a4ec7d268e2/Screen_Shot_2016-03-14_at_22.02.52.png)

See merge request !3171

New branch button on issues

Creates a button which creates a branch for you, referencing the original issue in the branch name. When creating the MR the text `Closes #iid` is appended to the description field.

The button; with styling

![Screenshot_from_2016-02-13_17-28-54](/uploads/9595fbfef88c10a499829beaa3db11c1/Screenshot_from_2016-02-13_17-28-54.png)

Links to the related branches on the issue

![Screenshot_from_2016-02-13_17-31-48](/uploads/ee7a78754eb5e2389f8671771bb59af9/Screenshot_from_2016-02-13_17-31-48.png)

Styled like the MR links

![Screenshot_from_2016-02-13_17-31-53](/uploads/c60130333a650a16f51b014aeb1458c3/Screenshot_from_2016-02-13_17-31-53.png)


Please provide input on the following; the CI repo on the GDK had the following happening with the current way I implemented the matching:

![Screenshot_from_2016-02-14_08-57-19](/uploads/35e7a3687a0fa801aba1ad66305ab2ff/Screenshot_from_2016-02-14_08-57-19.png)

Closes #3886 

cc @DouweM 


See merge request !2808

Fix horizontal overflow that occurs in the code tag

closes #14167 

### Before Fix
![Screen_Shot_2016-03-16_at_9.10.52_PM](/uploads/b4a282ffc33684983d7e2482b8e13a8f/Screen_Shot_2016-03-16_at_9.10.52_PM.png)

### After Fix
![Screen_Shot_2016-03-16_at_9.11.16_PM](/uploads/8acca3b46bfdbd929cc096ad070022e2/Screen_Shot_2016-03-16_at_9.11.16_PM.png)


See merge request !3255

Follow the CSS Style Guide rules for including a space after the property colon.

Fixes violations of SpaceAfterPropertyColon.

Discussed in #14299.

[ci skip]

cc: @rspeicher @jschatz1 

See merge request !3260