spec/features/issues/notes_on_issues_spec.rb sometimes gets stuck

Job #229713846 failed for 73609873:

Create notes on issues
  highlights the current user in a comment
  mentioning issue on a private project
    behaves like notes with reference
      creates a note with reference and cross references the issue
  mentioning issue on an internal project
    behaves like notes with reference
      creates a note with reference and cross references the issue
  mentioning issue on a public project
    behaves like notes with reference
      creates a note with reference and cross references the issue
  mentioning merge request on a private project
    behaves like notes with reference
Pulling docker image gitlab/gitlab-runner-helper:x86_64-ac2a293c ...
ERROR: Job failed: execution took longer than 1h30m0s seconds

It looks like the spec/features/issues/notes_on_issues_spec.rb gets stuck and then times out, causing a ~"master:flaky".