Block concurrent pipeline processings

## What does this MR do?

It's possible that two builds that succeed at the same will try to
concurrently process pipeline. This can lead to scenario when it will
fail to trigger next stages.

This MR makes sure that process of updating is blocking.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/21263

See merge request !6090

This reverts commit d836a359.

This reverts commit ff39ccfc.

Remove not-null constraint on lock_version column if it exists

Closes #21678

See merge request !6118

Remove default value for lock_version

From the very beginning we added `lock_version` column with default value, then we reverted that MR. A bit later we added that migration again but column's default value has been removed from migration. So if you installed GitLab form master it's possible that you have default value, which caused  the bug.

We don't need to change a CHANGELOG here I think.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/21527 and https://dev.gitlab.org/gitlab/organization/issues/971

See merge request !6111
Conflicts:
	db/schema.rb

Merge branch '21285-new-merge-request-source-and-target-branch-fields-filters-both-source-and-target-list' into 'master'

Fixed issue where filtering one dropdown will filter another on the page

## What does this MR do?

Moved `.option-hidden` to exist only in `SELECTABLE_CLASSES` as `NON_SELECTABLE_CLASSES` is used to re-show previously hidden elements.

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

## Why was this MR needed?

## What are the relevant issue numbers?

Closes #21285.

## Screenshots (if relevant)

![2016-08-24_15.59.16](/uploads/8282bd6507d10de61097956a57bd63cc/2016-08-24_15.59.16.gif)

## Does this MR meet the acceptance criteria?

- [ ] [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
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)
Closes #21285

See merge request !5985

Curved lines at top of pipeline graph

#### What does this MR do?
Adds curved lines to second-child of each column
## Are there points in the code the reviewer needs to double check?

#### Why was this MR needed?
To match the mockup

#### What are the relevant issue numbers?
Closes #21126 

#### Screenshots (if relevant)
![Screen_Shot_2016-08-26_at_9.31.49_AM](/uploads/318d3df4ce909daa0ef8ea8d989211c4/Screen_Shot_2016-08-26_at_9.31.49_AM.png)

See merge request !6033

Remove max height on pipelines graph

#### What does this MR do?
Removes max-height from pipeline graph

#### Why was this MR needed?
The height was originally put in place because some stages have ~20 tests, which ends up looking a little lopsided and there's a large amount of white space. The scrolling container, however, is not the best solution and ends up being more difficult to scroll around to find what you're looking for. For now we can remove the height, and eventually we'll have the similar tests collapsed.

#### Screenshots (if relevant)
Before:
![Screen_Shot_2016-08-24_at_11.32.39_AM](/uploads/1b32403548c6f7f4189a19279f13b84b/Screen_Shot_2016-08-24_at_11.32.39_AM.png)
After:
![Screen_Shot_2016-08-24_at_11.28.57_AM](/uploads/1327e37429b881265429f559d9d56482/Screen_Shot_2016-08-24_at_11.28.57_AM.png)

See merge request !5988

Remove ugly horizontal scrollbars in windows

## What does this MR do?
Removes horizontal scrollbars from pipelines view 

## Why was this MR needed?
It looked terrible.

## What are the relevant issue numbers?
Closes #21146

See merge request !5942

Removes leading space from hover state in graph links

#### What are the relevant issue numbers?
Closes #21123 

#### Screenshots (if relevant)
![Screen_Shot_2016-08-24_at_8.35.15_AM](/uploads/2dc583391f87c6d0a67f0535967c637f/Screen_Shot_2016-08-24_at_8.35.15_AM.png)

See merge request !5980

Add body as data-container on pipeline graph tooltip

## What does this MR do?
Fixed data tooltip getting cut off

## What are the relevant issue numbers?
Closes #21070 

## Screenshots (if relevant)
![Screen_Shot_2016-08-23_at_8.45.42_AM](/uploads/87f072cfc2fdeced6161db6bec46320a/Screen_Shot_2016-08-23_at_8.45.42_AM.png)

See merge request !5955

Ensure we update dropdown label after input has been added

Backport changes from https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/687

See merge request !5999

Do not enforce using a hash with hidden ci key

## What does this MR do?

This MR remove the validation rule that was to strict.

## Why was this MR needed?

Enforcing hidden CI job configuration to be a hash, narrows options of using YAML anchors, and was not backwards compatbile.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- Tests
  - [x] 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)

## What are the relevant issue numbers?

Closes #21512

See merge request !6079

Fix "Wiki" link not appearing in navigation for projects with external wiki

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

No

## What are the relevant issue numbers?

Closes #21446

## 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
  - [x] 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)
- [ ] 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 !6057

Fix resolving conflicts on forks

## What does this MR do?

When we resolve conflicts, we create a merge commit in the source branch with parents `[source_branch_head, target_branch_head]`. But when the MR is from a fork, `target_branch_head` might not exist in the source repo at all, so we need to fetch it if it isn't there. We can do this locally so it should be fast.

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

The `TestEnv` changes are needed to reset the branch refs if we're reusing a git directory locally - otherwise, there might not be conflicts!

## Why was this MR needed?

It's a bug in a new feature!

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] Added for this feature/bug
  - [x] 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)

## What are the relevant issue numbers?

Closes #21459.

See merge request !6082

Fix diff comments on legacy MRs

Allow diff commenting on MRs without complete diff refs. (Commenting would work before, but the JSON response would fail, so you'd only see your comment after a refresh.)

Is this really all I needed to do? I feel like there must be more to it 😊

It's a regression!

Closes #21211.

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] Added for this feature/bug
  - [x] 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 !6029
Conflicts:
	spec/features/merge_requests/diff_notes_spec.rb

docs: make sure to update 8.10-to-8.11 workhorse version too (see !5983)

## What does this MR do?

Make sure to remember the correct workhorse version for specific version update instructions for those of us still doing source installs.
Related to !5983.

See merge request !6049

Check for pipelines when setting page_gutter_class.

## What does this MR do?

Fixes regression issue related to the MR window sliding behind the right sidebar on page refresh. 

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

I'm getting stuck thinking about if/how to test this. Or maybe it just deserves a note somewhere about remembering to update `page_gutter_class` when a new route is added?

## Why was this MR needed?

This regression prevented users from using many features of the MR view.

## What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/21121

## Screenshots (if relevant)

Before: 
![Screen_Shot_2016-08-23_at_11.08.04_AM](/uploads/bad1a83569022a7fc699a978c5abef62/Screen_Shot_2016-08-23_at_11.08.04_AM.png)

After: 
![Screen_Shot_2016-08-23_at_11.07.46_AM](/uploads/6cbcb2f849c68dfc93d8a4b53089b06e/Screen_Shot_2016-08-23_at_11.07.46_AM.png)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [ ] Added for this feature/bug
  - [x] 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)

cc: @jschatz1 

See merge request !5952

Fix enormous IE11 fork button

## What does this MR do?
Puts a width on btn SVGs because IE can't handle `auto`

## What are the relevant issue numbers?
Closes #21099

See merge request !5982

Use new image for Issue Board page

Replace the Issue Board image with a new one

See merge request !6013

Fix wrong Koding link



See merge request !6030

Automatically expand hidden discussions when accessed via a permalink hash (closes #19304)

## What does this MR do?

Addresses "Auto-expand a discussion note when we arrive via anchor" (issue #19304)

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

Let me know if the code is consistent with community standards (not 100% sure about indentation of chained jQuery actions)

I don't think this MR warrants any unit tests or documentation, but let me know if you disagree.  I'll add the requisite CHANGELOG entry upon approval.

## Why was this MR needed?

Currently, if a discussion is accessed via a permalink to an "outdated" diff discussion, the anchor will not bring you to the expected part of the page.

## What are the relevant issue numbers?

#19304 

## 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)
- 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 !5585

Label list shows all issues (opened or closed) with that label

## What does this MR do?

Change the label list to shows all issues (opened or closed) with that label.

## What are the relevant issue numbers?

Closes #21257

See merge request !5991

Handle non-UTF-8 conflicts gracefully

## What does this MR do?

If a conflict file isn't in a UTF-8-compatible encoding, we can't resolve it in the UI.

## What are the relevant issue numbers?

Closes #21247. 

See merge request !5961

Fix changelog



See merge request !6035

Fix external issue tracker "Issues" link leading to 404s

## What does this MR do?

This MR fixes the redirection to the wrong URL when using an external issue tracker, such as JIRA or Redmine.  a70431f8 modified the behavior to link to the external issue tracker
issues URL instead of the project path URL. This restores the previous behavior.

## Why was this MR needed?

The issues URL often has `:id` associated with it for linking mentioned issues.
For external issue trackers, the project page is the intended target.

## What are the relevant issue numbers?

Closes #21252

Related to #21402

See merge request !6006

Handle unavailable system info

## What does this MR do?

Handle the case where we can't get system info without blowing up. As this is the first tab in the monitoring section, it's difficult to get to the other tabs if this page throws a 500. Also be more specific about the info we want, so we don't fail on something we don't care about (like `/proc/net/dev`).

## Why was this MR needed?

grsecurity can prevent users from reading `/proc`, which is what Vmstat uses to find CPU and memory info.

## What are the relevant issue numbers?

Closes #21378.

See merge request !5989

last_push_event widget considers fork events on the main project

Push events on the fork of the current project are considered to be shown besides the push events on the current project. Before we just consider fork events if exists a fork so we miss current project events if the current user has a fork.

Closes #20254

See merge request !5978

Does not halt the GitHub import process when an error occurs

## What are the relevant issue numbers?

Fixes #20385 

https://gitlab.com/gitlab-org/gitlab-ce/issues/20149

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] 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 !5763

Use gitlab-workhorse 0.7.11

Versions 0.7.9 and 0.7.10 crash on previously valid 'authBackend'
settings.

I don't know how many people are affected by this, 'normal' Omnibus
installations are not. (If they were gitlab.com would have stopped
working :) ). Still this is something we should not ship.
Unfortunately 8-11-stable uses 0.7.10 (but 8.11.0 does not). So I
think we need to put this in the next 8.11 patch release.

See merge request !5983

Change slash commands docs location



See merge request !5937