Its time for 8.9

See merge request !4262

Enable multiple Rubocop cops that can be enabled

See https://gitlab.com/gitlab-org/gitlab-ce/issues/17406

This enabled following cops:

```text
Lint/CircularArgumentReference:
  Description: Default values in optional keyword arguments and optional ordinal arguments
----------------
Lint/ConditionPosition:
  Description: Checks for condition placed in a confusing position relative to the keyword.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#same-line-condition
----------------
Lint/Debugger:
  Description: Check for debugger calls.
----------------
Lint/DefEndAlignment:
  Description: Align ends corresponding to defs correctly.
----------------
Lint/DuplicateMethods:
  Description: Check for duplicate method definitions.
----------------
Lint/DuplicatedKey:
  Description: Check for duplicate keys in hash literals.
----------------
Lint/EachWithObjectArgument:
  Description: Check for immutable argument given to each_with_object.
----------------
Lint/ElseLayout:
  Description: Check for odd code arrangement in an else block.
----------------
Lint/EmptyEnsure:
  Description: Checks for empty ensure block.
----------------
Lint/EmptyInterpolation:
  Description: Checks for empty string interpolation.
----------------
Lint/EndAlignment:
  Description: Align ends correctly.
----------------
Lint/EndInMethod:
  Description: END blocks should not be placed inside method definitions.
----------------
Lint/EnsureReturn:
  Description: Do not use return in an ensure block.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#no-return-ensure
----------------
Lint/Eval:
  Description: The use of eval represents a serious security risk.
----------------
Lint/FloatOutOfRange:
  Description: Catches floating-point literals too large or small for Ruby to represent.
----------------
Lint/FormatParameterMismatch:
  Description: The number of parameters to format/sprint must match the fields.
----------------
Lint/ImplicitStringConcatenation:
  Description: Checks for adjacent string literals on the same line, which could better
    be represented as a single string literal.
----------------
Lint/InvalidCharacterLiteral:
  Description: Checks for invalid character literals with a non-escaped whitespace character.
----------------
Lint/LiteralInInterpolation:
  Description: Checks for literals used in interpolation.
----------------
Lint/NestedMethodDefinition:
  Description: Do not use nested method definitions.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#no-nested-methods
----------------
Lint/NextWithoutAccumulator:
  Description: Do not omit the accumulator when calling `next` in a `reduce`/`inject`
    block.
----------------
Lint/RandOne:
  Description: Checks for `rand(1)` calls. Such calls always return `0` and most likely
    a mistake.
----------------
Lint/RequireParentheses:
  Description: Use parentheses in the method call to avoid confusion about precedence.
----------------
Lint/UnreachableCode:
  Description: Unreachable code.
----------------
Lint/UselessComparison:
  Description: Checks for comparison of something with itself.
----------------
Lint/UselessElseWithoutRescue:
  Description: Checks for useless `else` in `begin..end` without `rescue`.
----------------
Lint/UselessSetterCall:
  Description: Checks for useless setter call to a local variable.
----------------
Lint/Void:
  Description: Possible use of operator/literal/variable in void context.
----------------
Performance/DoubleStartEndWith:
  Description: Use `str.{start,end}_with?(x, ..., y, ...)` instead of `str.{start,end}_with?(x,
    ...) || str.{start,end}_with?(y, ...)`.
----------------
Performance/RedundantSortBy:
  Description: Use `sort` instead of `sort_by { |x| x }`.
----------------
Rails/FindBy:
  Description: Prefer find_by over where.first.
  Include:
  - app/models/**/*.rb
----------------
Rails/FindEach:
  Description: Prefer all.find_each over all.find.
  Include:
  - app/models/**/*.rb
----------------
Rails/PluralizationGrammar:
  Description: Checks for incorrect grammar when using methods like `3.day.ago`.
----------------
Rails/ScopeArgs:
  Description: Checks the arguments of ActiveRecord scopes.
  Include:
  - app/models/**/*.rb
```

See merge request !4261

Enable Style/SpaceAroundKeyword cop and fix offenses

Ref: https://gitlab.com/gitlab-org/gitlab-ce/issues/17478

See merge request !4259

Update rubocop to 0.40.0

See merge request !4258

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

Enable Style/InfiniteLoop Rubocop cop

This MR enabled Style/InfiniteLoop Rubocop cop, and fixes offenses.

See https://gitlab.com/gitlab-org/gitlab-ce/issues/17478

See merge request !4257

This enables multiple Rubocop cops that already conform to our codebase
and do not require fixes.

Enable Performance/RangeInclude cop and fix single offense

Ref: https://gitlab.com/gitlab-org/gitlab-ce/issues/17478

See merge request !4255

Enable Performance/StartWith cop and fix offenses

Ref: https://gitlab.com/gitlab-org/gitlab-ce/issues/17478

See merge request !4256

Fix builds page

Fixes #17736    
Fixes #17703 

- Move tags into column
- Put column headers back

<img src="/uploads/57609fd2d65c3b80f57b32cbbe316653/Screen_Shot_2016-05-23_at_10.20.37_AM.png" width="800px">    



See merge request !4249

Enable Style/DefWithParentheses cop and fix single offense

Ref: https://gitlab.com/gitlab-org/gitlab-ce/issues/17478

See merge request !4254

Initial version of user documentation of container registry

cc @axil


See merge request !4244

Fix Error 500 in CI charts by gracefully handling commits with no durations

## What does this MR do?

In the CI charts, this MR reports the duration of a commit to 0 if it is `nil`.

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

Should we omit this commit from the chart or set it to some other value?

## Why was this MR needed?

We were getting an Error 500 here: https://gitlab.com/gitlab-org/gitlab-ce/graphs/master/ci

## What are the relevant issue numbers?

#17730 


See merge request !4245

Use gitlab-workhorse 0.7.3

Relax workhorse listen socket permissions.

See merge request !4252

Added remove due date button

In the sidebar when there is a due date a link to remove due date becomes visible

![remove-due-date](/uploads/126baa61f5ec44ce503ce374d5331ba6/remove-due-date.gif)

Closes #17392

See merge request !4209

In the sidebar when there is a due date, a link to remove due date becomes visible

Closes #17392

Closes #17730

Fix Error 500 when accessing application settings due to nil disabled OAuth sign-in sources

## What does this MR do?

When upgrading to GitLab 8.8, an admin would encounter an Error 500 due to a `nil` `disabled_oauth_sign_in_sources`. This MR ensures that the value will be a blank array if empty.

Closes #17564

See merge request !4242

[ci skip]

[ci skip]

Fix some specs which would have broken in 2017 to not break anymore by using a dynamic year value.

Static year values would have caused the test suite to fail on these in the future, so I replaced 'em.

That's pretty much all there is to this MR.

See merge request !4241