Multiple assignees review: merge upstream
This MR merges recent master to multiple_assignees_review
(https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1541)
Conflicts:
✔️both modified: app/assets/javascripts/boards/components/board_sidebar.js
both modified: app/assets/javascripts/boards/components/issue_card_inner.js
both modified: app/assets/javascripts/boards/components/new_list_dropdown.js
both modified: app/assets/javascripts/users_select.js
both modified: app/assets/stylesheets/pages/boards.scss
both modified: app/assets/stylesheets/pages/issuable.scss
✔️both modified: app/models/concerns/issuable.rb
✔️both modified: app/models/issue.rb
✔️both modified: app/models/milestone.rb
✔️both modified: app/models/user.rb
✔️both modified: app/views/notify/new_issue_email.html.haml
✔️both modified: app/views/notify/new_mention_in_issue_email.html.haml
both modified: app/views/shared/issuable/_sidebar.html.haml
✔️both modified: app/views/shared/milestones/_issuable.html.haml
both modified: config/webpack.config.js
✔️both modified: db/schema.rb
✔️both modified: doc/api/issues.md
✔️both modified: spec/features/dashboard/issuables_counter_spec.rb
✔️both modified: spec/features/issues/filtered_search/filter_issues_spec.rb
✔️both modified: spec/features/search_spec.rb
✔️both modified: spec/finders/issues_finder_spec.rb
✔️both modified: spec/mailers/notify_spec.rb
✔️both modified: spec/models/issue_spec.rb
✔️deleted by them: spec/policies/issues_policy_spec.rb
✔️both modified: spec/requests/api/issues_spec.rb
✔️both modified: spec/requests/api/v3/issues_spec.rb
✔️both modified: spec/services/issues/update_service_spec.rb
✔️both modified: spec/services/users/destroy_service_spec.rb
/cc @ClemMakesApps