* upstream/master: (353 commits)
  Put some admin settings in dropdown
  Add styleguide on configuration settings documentation
  Remove Duplicated keys add UNIQUE index to fingerprint
  Avoid autoload issue such as 'Mail::Parsers::AddressStruct'
  Move appearance settings as sub tab to application settings
  use rails root join
  fixed a couple of errors spotted in production
  Fix RangeError exceptions when referring to issues or merge requests outside of max database values
  Fix bug in `WikiLinkFilter`.
  Grammar and typographic changes to artifacts documentation
  Tweak grammar
  Small frontend code fixes and restore 8a2d88f commit
  Warn about admin privilege to disable GitHub Webhooks
  Listing GH Webhooks doesn't stop import process for non GH admin users
  fixup! updated docs for api endpoint award emoji
  Update CHANGELOG
  Ensure Todos counters doesn't count Todos for projects pending delete
  Add endpoints for award emoji on notes
  Sort API endpoints and implement feedback
  Add endpoints for Award Emoji
  ...

Fix error when CI job variables key used but not specified

## What does this MR do?

This MR fixes a an error when CI job variables specified, but not defined:

```yaml
image: ruby:2.2

test:
  variables:
  script:
     - rspec
```

## What are the relevant issue numbers?

Closes #18764  
Follow up discussion in: #18775 

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] 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] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4745

* upstream/master: (337 commits)
  Update CHANGELOG for !4659
  Center the header logo for all Devise emails
  Add previews for all customized Devise emails
  Customize the Devise `unlock_instructions` email
  Customize the Devise `reset_password_instructions` email
  Customize the Devise `password_change` emails
  Use gitlab-git 10.2.0
  Use Git cached counters on project show page
  Fix indentation scss-lint errors
  Added title attribute to enties in tree view Closes #18353
  Banzai::Filter::ExternalLinkFilter use XPath
  Reduce queries in IssueReferenceFilter
  Use gitlab_git 10.1.4
  Fixed ordering in Project.find_with_namespace
  Fix images in emails
  Banzai::Filter::UploadLinkFilter use XPath
  Turn Group#owners into a has_many association
  Make project_id nullable
  CHANGELOG [ci skip]
  CHANGELOG [ci skip]
  ...

Currently the RegexpError can be raised when processing next stage which leads to 500 in different places of code base.
This adds early check that regexps used in only and except are valid.

* master: (198 commits)
  Set inverse_of for Project/Services relation
  Fix admin hooks spec
  Prevent default disabled buttons and links.
  Add index on `requested_at` to the `members` table
  Rearrange order of tabs
  Fix admin active tab tests
  Show created_at in table column
  Nest li elements directly under ul
  Move builds tab to admin overview
  Add monitoring link with subtabs
  Add sub links to overview
  Add counter for abuse reports
  Remove admin layout-nav counters
  Move admin nav to horizontal layout nav
  Eager load project relations in IssueParser
  Use validate and required for environment and project
  Award Emoji can't be awarded on system notes backend
  Get rid of Gitlab::ShellEnv
  Update CHANGELOG.
  Fix project star tooltip on the fly.
  ...

Conflicts:
	app/services/ci/create_builds_service.rb

* master: (147 commits)
  Update CHANGELOG
  Remove deprecated issues_tracker and issues_tracker_id from project
  Schema doesn’t reflect the changes of the last 3 migrations
  Revert CHANGELOG
  Also rename "find" in the specs
  Change to new Notes styleguide
  Add guide on changing a document's location
  Change logs.md location in README
  Move logs/logs.md to administration/logs.md
  Make "four phase test"
  Only show branches for revert / cherry-pick
  Instrument all Banzai::ReferenceParser classes
  Removed old comment from update_column_in_batches
  Update columns in batches until no rows are left
  Remove counters from Pipeline navigation
  Handle NULL migration errors in migration helpers
  Fix typo causing related branches to Error 500
  Improved SVG sanitizer specs to include smoke tests for clean.
  Refactored SVG sanitizer
  Added SVG sanitizer fix to the changelog
  ...

# Conflicts:
#	db/schema.rb

# Conflicts:
#	lib/ci/gitlab_ci_yaml_processor.rb