Merge branch '18446-when-this-merge-request-is-accepted-this-issue-will-be-closed-automatically-rendered-twice' into 'master'

Resolve ""When this merge request is accepted, this issue will be closed automatically" rendered twice"

## What does this MR do?

1. Only show the above text when there is an MR that will close the issue, and even then, only show it once.
2. Apply 98f147e84d2bd8f2278452ac0852118452c76d4a to a bunch of other places that need it.

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

¯\_(ツ)_/¯

## Why was this MR needed?

Some pages were broken.

## What are the relevant issue numbers?

Fixes #18446.

## Screenshots (if relevant)

Before:
![image](/uploads/23cfaf95b7c798f22963ff67f78a803b/image.png)

After:
![image](/uploads/ca9c538069ba52e53858c69387738521/image.png)

## 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)

See merge request !4594

Improve SVG sanitizer to handle namespaced attributes

* Small refactor in the SVG sanitizer
* Enable already whitelisted namespaced attributes to be allowed
* Disable `xlink:href`to reference any external resource

Fixes #18100 

See merge request !4427

Fix Error 500 when using closes_issues API with an external issue tracker

Closes #18484

See merge request !4608

Closes #18484

Improvements to offscreen navigation

Improvements on top of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4579 based on mockups from https://gitlab.com/gitlab-org/gitlab-ce/issues/18417#note_12389766

See merge request !4607

Resolve "Hide Left sidebar paradigm"

## What does this MR do?
Hides the nav bar by default & centers the tanuki logo in the top nav

## Why was this MR needed?
UX

## What are the relevant issue numbers?
Closes #18417 

## Screenshots (if relevant)
![Screen_Shot_2016-06-10_at_12.49.10_PM](/uploads/c281e4c9de1c1bc9af59ebfa8d2bd18b/Screen_Shot_2016-06-10_at_12.49.10_PM.png)
![Screen_Shot_2016-06-10_at_12.49.27_PM](/uploads/635e0a88230105faa5527f6632899ddb/Screen_Shot_2016-06-10_at_12.49.27_PM.png)
<img src="/uploads/3001a9c723037012f1b86cfacfb1225e/Screen_Shot_2016-06-10_at_12.51.41_PM.png" width="500px">

See merge request !4579

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Fixed search form padding

## What does this MR do?

Corrects the padding of the search form.

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

Ney.

## Why was this MR needed?

UX

## What are the relevant issue numbers?

Closes #18463.

## Screenshots (if relevant)

![Screen_Shot_2016-06-10_at_14.07.32](/uploads/e4d127c66cf7fa3286279367d6e4ea7c/Screen_Shot_2016-06-10_at_14.07.32.png)

## 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
- [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 !4591

Only create the backup directory if it is local

Closes #12710

See merge request !4551

Closes #12710

Add Project.where_paths_in

In https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4410 I'm working on reducing the SQL queries needed to render Markdown. One reason for the large amount of queries is executing a large number of queries needed to find projects and related data. Basically `Project.find_with_namespace` is called in a loop and then any relations have to be retrieved separately.

By using `Project.where_paths_in` we can work around this by doing something like:

```ruby
project_paths = [...] # populated by some method
projects = Project.where_paths_in(project_paths).includes(:namespace, ...)
```

Ref: https://gitlab.com/gitlab-org/gitlab-ce/issues/18042

See merge request !4535