1. Don't use case statements for dispatch anymore. This leads to a lot
   of duplication, and makes the logic harder to follow.

2. Remove duplicated logic.

    - For example, the `can_push_to_branch?` exists, but we also have a
      different way of checking the same condition within `change_access_check`.

    - This kind of duplication is removed, and the `can_push_to_branch?`
      method is used in both places.

3. Move checks returning true/false to `UserAccess`.

    - All public methods in `GitAccess` now return an instance of
      `GitAccessStatus`. Previously, some methods would return
      true/false as well, which was confusing.

    - It makes sense for these kinds of checks to be at the level of a
      user, so the `UserAccess` class was repurposed for this. The prior
      `UserAccess.allowed?` classmethod is converted into an instance
      method.

    - All external uses of these checks have been migrated to use the
      `UserAccess` class

4. Move the "change_access_check" into a separate class.

    - Create the `GitAccess::ChangeAccessCheck` class to run these
      checks, which are quite substantial.

    - `ChangeAccessCheck` returns an instance of `GitAccessStatus` as
      well.

5. Break out the boolean logic in `ChangeAccessCheck` into `if/else`
   chains - this seems more readable.

6. I can understand that this might look like overkill for !4892, but I
   think this is a good opportunity to clean it up.

    - http://martinfowler.com/bliki/OpportunisticRefactoring.html

1. When a merge request is being merged, save the merge commit SHA in
   the `in_progress_merge_commit_sha` database column.

2. The `pre-receive` hook looks for any locked (in progress) merge
   request with `in_progress_merge_commit_sha` matching the `newrev` it
   is passed.

3. If it finds a matching MR, the merge is legitimate.

4. Update `git_access_spec` to test the behaviour we added here. Also
   refactored this spec a bit to make it easier to add more contexts / conditions.

- Cherry-picked from `mvestergaard:branch-protection-dev-merge`
- https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4220

Render inline diffs for multiple changed lines following eachother

Before:

![Screen_Shot_2016-07-11_at_00.08.27](/uploads/b14664211e0f5cef6e77a78eadfcbcdf/Screen_Shot_2016-07-11_at_00.08.27.png)

After:

![Screen_Shot_2016-07-11_at_00.07.34](/uploads/567be631869a4867a2edf6ff7eda6369/Screen_Shot_2016-07-11_at_00.07.34.png)

See merge request !5174

Delete award emoji when deleting a user

## What does this MR do?

Fix the problem where a user's award emoji aren't deleted when the user is deleted.

## Are there points in the code the reviewer needs to double check?

The corresponding SELECT for the migration runs in 0.3s on staging, but I can't test the delete there or on production easily. It should be reasonably quick.

## Why was this MR needed?

There was a typo in an association 😱 

## What are the relevant issue numbers?

Closes #19693.

## Screenshots (if relevant)

Nope.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- ~~[Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)~~
- ~~API support added~~
- Tests
  - ~~Added for this feature/bug~~
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5216

Change running status color to blue; update icon to spinner

## What does this MR do?
Changes running status color to blue    
Updates icon to spinner to differentiate from `pending`

## What are the relevant issue numbers?
Closes #17702   
Part of https://gitlab.com/gitlab-org/gitlab-ce/issues/18920

## Screenshots (if relevant)
![Screen_Shot_2016-07-12_at_4.34.48_PM](/uploads/8f6bb36a7a8fe99db1ec1ef8e9db6388/Screen_Shot_2016-07-12_at_4.34.48_PM.png)


See merge request !5222

Add margin to filter labels

## What does this MR do?
Adds margin to filter labels

## Why was this MR needed?
It was pretty ugly before

## What are the relevant issue numbers?
Closes #19708

## Screenshots (if relevant)
![Screen_Shot_2016-07-11_at_4.42.05_PM](/uploads/55c049e442a16a06c14bb9394137cc87/Screen_Shot_2016-07-11_at_4.42.05_PM.png)


See merge request !5194

Update header block class on snippets page

## What does this MR do?
Changes gray block in `Snippets` to new white sub header style

## What are the relevant issue numbers?
Closes #19692 

## Screenshots (if relevant)
![Screen_Shot_2016-07-11_at_4.17.10_PM](/uploads/f4cea2d019d30fc7c6adc7e3b26590b4/Screen_Shot_2016-07-11_at_4.17.10_PM.png)

See merge request !5192

Resolve "Design updates for Builds & Pipelines"

## What does this MR do?
Updates pipelines design

## What are the relevant issue numbers?
Part of  #18920    
Closes #17760  
Closes #18479    
Closes #19618 

## Screenshots (if relevant)
![Screen_Shot_2016-07-11_at_2.44.22_PM](/uploads/5048928d86093802d84c3bd7f7c5dc85/Screen_Shot_2016-07-11_at_2.44.22_PM.png)
![Screen_Shot_2016-07-11_at_2.32.17_PM](/uploads/a7ab94c8042d33bd06ef633f62bf1c99/Screen_Shot_2016-07-11_at_2.32.17_PM.png)
![Screen_Shot_2016-07-11_at_2.44.43_PM](/uploads/8aa63229ad75d373c30f342d5c86c007/Screen_Shot_2016-07-11_at_2.44.43_PM.png)

See merge request !5156

Add 2FA check to the OAuth authentication mechanism

Needed for https://gitlab.com/gitlab-org/gitlab-ce/issues/19312

2FA checks were not being performed when logging in via any of the OAuth providers. Just LDAP had the check. This MR fixes that.

See merge request !1976

Use number_with_delimiter for Todos pending/done tab counts

See merge request !5199

Avoid `describe`-ing symbols in specs

See merge request !5195

Change new pipeline to run pipeline

## What does this MR do?
Change text of button from `New pipeline` to `Run pipeline`

## What are the relevant issue numbers?
Closes #18935    
Part of  #18920 

## Screenshots (if relevant)
![Screen_Shot_2016-07-06_at_12.15.36_PM](/uploads/2e0413b802118781dc5a29c7f1c105b8/Screen_Shot_2016-07-06_at_12.15.36_PM.png)

See merge request !5119

[ci skip]

Add approval required todos

Ports the 'approval required' todo type from EE - https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/547

See merge request !5217

Resolve "Possible sidebar improvements based"

## What does this MR do?
Cleans up the sidebar

## Are there points in the code the reviewer needs to double check?
@dzaporozhets it looks like your screenshot has more padding on the left and right of the sidebar, but if you do that then the hamburger icon doesn't match the placement on the top nav, and it makes it look like icon is shifting back and forth. 

## What are the relevant issue numbers?
Part of #19659 

## Screenshots (if relevant)
![nav](/uploads/693d8a21bac464fc7dd40a51cb7dccda/nav.gif)

See merge request !5211

Remove Hound CI and Teatro config

## What does this MR do?

Since we moved to gitlab.com we don't use Hound CI and Teatro anymore. Instead we have rubocop.



See merge request !5089

Optimistic locking for Issue and Merge Requests

## What does this MR do?

It implements Optimistic Locking http://api.rubyonrails.org/classes/ActiveRecord/Locking/Optimistic.html for Issues and MRs but in a bit custom way. We use it for cases when either title or description field is involved in the change.

## Why was this MR needed?

We have to prevent data losing.

## What are the relevant issue numbers?
https://gitlab.com/gitlab-org/gitlab-ce/issues/12940

## Screenshots (if relevant)

![Screen_Shot_2016-07-09_at_15.33.02](/uploads/2efbe547a12fda93bce347fa711438d7/Screen_Shot_2016-07-09_at_15.33.02.png)


See merge request !5146

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/17877 .

This change adds 'defense in depth' against 'Host' HTTP header
injection. It affects normal users in the following way. Suppose your
GitLab server has IP address 1.2.3.4 and hostname gitlab.example.com.
Currently, if you enter 1.2.3.4 in your browser, you get redirected to
1.2.3.4/users/sign_in. After this change, you get redirected from
1.2.3.4 to gitlab.example.com/users/sign_in. This is because the
address you typed in the address bar of your browser ('1.2.3.4'),
which gets stored in the 'Host' header, is now being overwritten to
'gitlab.example.com' in NGINX.

In this change we also make NGINX clear the 'X-Forwarded-Host' header
because Ruby on Rails also uses that header the same wayas the 'Host'
header.

We think that for most GitLab servers this is the right behavior, and
if not then administrators can change this behavior themselves at the
NGINX level.

Cache todos pending/done dashboard query counts

See #19273

See merge request !5175

Remove unused RelativeUrl spec support file

See merge request !5207