* master: (98 commits)
  Enable Style/EmptyLines cop, remove redundant ones
  Update CHANGELOG
  Cache results from jQuery selectors to retrieve namespace name
  Fix import button when import fail due the namespace already been taken
  Fix snippets comments not displayed
  Fix emoji paths in relative root configurations
  Exclude requesters from Project#members, Group#members and User#members
  Upgrade Thin from 1.6.1 to 1.7.0.
  Many squashed commits
  Cache autocomplete results
  Upgrade Sidekiq from 4.1.2 to 4.1.4.
  Upgrade seed-fu from 2.3.5 to 2.3.6
  use has_many relationship with events
  Support creating a todo on issuables via API
  Expose target, filter by state as string
  Add todos API documentation and changelog
  Improve the request / withdraw access button
  Metrics for Rouge::Plugins::Redcarpet and Rouge::Formatters::HTMLGitlab
  Groundwork for Kerberos SPNEGO (EE feature)
  Update CHANGELOG 8.9.5 for runners related fixes
  ...

Postgres and MySQL don't guarantee that pagination with `LIMIT` and
`OFFSET` will work if the ordering isn't unique. From the Postgres docs:

> When using `LIMIT`, it is important to use an `ORDER BY` clause that
> constrains the result rows into a unique order. Otherwise you will get
> an unpredictable subset of the query's rows

Before:

    [1] pry(main)> issues = 1.upto(Issue.count).map { |i| Issue.sort('priority').page(i).per(1).map(&:id) }.flatten
    [2] pry(main)> issues.count
    => 81
    [3] pry(main)> issues.uniq.count
    => 42

After:

    [1] pry(main)> issues = 1.upto(Issue.count).map { |i| Issue.sort('priority').page(i).per(1).map(&:id) }.flatten
    [2] pry(main)> issues.count
    => 81
    [3] pry(main)> issues.uniq.count
    => 81

When using #XYZ in Markdown text, if XYZ exceeds the maximum value of a signed 32-bit integer, we
get an exception when the Markdown render attempts to run `where(iids: XYZ)`. Introduce a method
that will throw out out-of-bounds values.

Closes #18777