### Summary The MR widget shows `Could not retrieve the pipeline status` instead of pipeline status. **But** the pipeline tab in the widget shows the pipelines without issue. ### Steps to reproduce Unable to reproduce this issue, because I don't know what's causing things to get into this state. ### Example Project This MR is closed and merged, but it should show the same behavior: https://gitlab.com/cody/auto-devops-templates/merge_requests/1. I'm not sure how this MR got into this state, as I only _accidentally_ reproduced the bug. ### What is the current *bug* behavior? The `group/project/merge_requests/:id/widget.json` endpoint returns no pipeline object. I had a chance to trace through the code and test some things with a self-managed customer that was experiencing this behavior. I think this is happening because `actual_head_pipeline` is returning `nil` for some merge requests. I can see in [serializers/merge_request_poll_widget_entity.rb#L20](https://gitlab.com/gitlab-org/gitlab/blob/33df3081195274e7eb6de1e4090a50a04b168844/app/serializers/merge_request_poll_widget_entity.rb#L20) that `:actual_head_pipeline` is what gets exposed as `:pipeline`. I think this might be a regression that was introduced with https://gitlab.com/gitlab-org/gitlab-foss/issues/40004. Running `update_head_pipeline` fixes the issue. ### What is the expected *correct* behavior? Pipeline status is returned and displayed in the MR widget. ### Relevant logs and/or screenshots  Here's the text from a rails console session where we were testing some things: ```ruby irb(main):003:0> mr = MergeRequest.find_by(project: proj, iid: 154) => #<MergeRequest id:217665 group/project!154> irb(main):004:0> mr.attributes => {"id"=>217665, "target_branch"=>"master", "source_branch"=>"something-bugfix/other-words-here", "source_project_id"=>21708, "author_id"=>9986, "assignee_id"=>nil, "title"=>"MR title here", "created_at"=>Fri, 01 Nov 2019 22:07:07 UTC +00:00, "updated_at"=>Mon, 04 Nov 2019 18:37:59 UTC +00:00, "milestone_id"=>nil, "state"=>"closed", "merge_status"=>"can_be_merged", "target_project_id"=>21708, "iid"=>154, "description"=>"description here", "updated_by_id"=>nil, "merge_error"=>nil, "merge_params"=>{"force_remove_source_branch"=>"0"}, "merge_when_pipeline_succeeds"=>false, "merge_user_id"=>nil, "merge_commit_sha"=>nil, "approvals_before_merge"=>nil, "rebase_commit_sha"=>nil, "in_progress_merge_commit_sha"=>nil, "lock_version"=>0, "time_estimate"=>0, "squash"=>false, "last_edited_at"=>nil, "last_edited_by_id"=>nil, "head_pipeline_id"=>640263, "merge_jid"=>nil, "discussion_locked"=>nil, "latest_merge_request_diff_id"=>495888, "allow_maintainer_to_push"=>nil, "state_id"=>2} irb(main):009:0> mr.state => "closed" irb(main):010:0> mr.has_ci? => true irb(main):011:0> mr.broken? => false irb(main):012:0> mr.branch_missing? => false irb(main):013:0> mr.head_pipeline => #<Ci::Pipeline id: 640263, ref: "something-bugfix/other-words-here", sha: "461d1621094d547866a0985ef8a2b95d96ae3247", before_sha: nil, created_at: "2019-11-04 18:52:43", updated_at: "2019-11-04 18:57:49", tag: false, yaml_errors: nil, committed_at: nil, project_id: 21708, status: "success", started_at: "2019-11-04 18:52:58", finished_at: "2019-11-04 18:57:49", duration: 0, user_id: 7283, lock_version: 3, auto_canceled_by_id: nil, pipeline_schedule_id: nil, source: "external", protected: false, config_source: nil, failure_reason: nil, iid: 691, merge_request_id: nil, source_sha: nil, target_sha: nil> irb(main):014:0> mr.actual_head_pipeline => nil irb(main):015:0> mr.base_pipeline => nil irb(main):016:0> mr.head_pipeline.attributes => {"id"=>640263, "ref"=>"something-bugfix/other-words-here", "sha"=>"461d1621094d547866a0985ef8a2b95d96ae3247", "before_sha"=>nil, "created_at"=>Mon, 04 Nov 2019 18:52:43 UTC +00:00, "updated_at"=>Mon, 04 Nov 2019 18:57:49 UTC +00:00, "tag"=>false, "yaml_errors"=>nil, "committed_at"=>nil, "project_id"=>21708, "status"=>"success", "started_at"=>Mon, 04 Nov 2019 18:52:58 UTC +00:00, "finished_at"=>Mon, 04 Nov 2019 18:57:49 UTC +00:00, "duration"=>0, "user_id"=>7283, "lock_version"=>3, "auto_canceled_by_id"=>nil, "pipeline_schedule_id"=>nil, "source"=>"external", "protected"=>false, "config_source"=>nil, "failure_reason"=>nil, "iid"=>691, "merge_request_id"=>nil, "source_sha"=>nil, "target_sha"=>nil} irb(main):017:0> mr.reload_head_pipeline => #<Ci::Pipeline id: 640263, ref: "something-bugfix/other-words-here", sha: "461d1621094d547866a0985ef8a2b95d96ae3247", before_sha: nil, created_at: "2019-11-04 18:52:43", updated_at: "2019-11-04 18:57:49", tag: false, yaml_errors: nil, committed_at: nil, project_id: 21708, status: "success", started_at: "2019-11-04 18:52:58", finished_at: "2019-11-04 18:57:49", duration: 0, user_id: 7283, lock_version: 3, auto_canceled_by_id: nil, pipeline_schedule_id: nil, source: "external", protected: false, config_source: nil, failure_reason: nil, iid: 691, merge_request_id: nil, source_sha: nil, target_sha: nil> irb(main):018:0> mr.update_head_pipeline => true irb(main):019:0> mr.head_pipeline.attributes => {"id"=>640234, "ref"=>"something-bugfix/other-words-here", "sha"=>"c7feb6c61525ecb4c9a010ccd095e57367d004f6", "before_sha"=>nil, "created_at"=>Mon, 04 Nov 2019 18:38:31 UTC +00:00, "updated_at"=>Mon, 04 Nov 2019 18:43:47 UTC +00:00, "tag"=>false, "yaml_errors"=>nil, "committed_at"=>nil, "project_id"=>21708, "status"=>"success", "started_at"=>Mon, 04 Nov 2019 18:38:48 UTC +00:00, "finished_at"=>Mon, 04 Nov 2019 18:43:47 UTC +00:00, "duration"=>0, "user_id"=>7283, "lock_version"=>3, "auto_canceled_by_id"=>nil, "pipeline_schedule_id"=>nil, "source"=>"external", "protected"=>false, "config_source"=>nil, "failure_reason"=>nil, "iid"=>690, "merge_request_id"=>nil, "source_sha"=>nil, "target_sha"=>nil} irb(main):024:0> Ci::Pipeline.find 640263 => #<Ci::Pipeline id: 640263, ref: "something-bugfix/other-words-here", sha: "461d1621094d547866a0985ef8a2b95d96ae3247", before_sha: nil, created_at: "2019-11-04 18:52:43", updated_at: "2019-11-04 18:57:49", tag: false, yaml_errors: nil, committed_at: nil, project_id: 21708, status: "success", started_at: "2019-11-04 18:52:58", finished_at: "2019-11-04 18:57:49", duration: 0, user_id: 7283, lock_version: 3, auto_canceled_by_id: nil, pipeline_schedule_id: nil, source: "external", protected: false, config_source: nil, failure_reason: nil, iid: 691, merge_request_id: nil, source_sha: nil, target_sha: nil> irb(main):025:0> Ci::Pipeline.find 640234 => #<Ci::Pipeline id: 640234, ref: "something-bugfix/other-words-here", sha: "c7feb6c61525ecb4c9a010ccd095e57367d004f6", before_sha: nil, created_at: "2019-11-04 18:38:31", updated_at: "2019-11-04 18:43:47", tag: false, yaml_errors: nil, committed_at: nil, project_id: 21708, status: "success", started_at: "2019-11-04 18:38:48", finished_at: "2019-11-04 18:43:47", duration: 0, user_id: 7283, lock_version: 3, auto_canceled_by_id: nil, pipeline_schedule_id: nil, source: "external", protected: false, config_source: nil, failure_reason: nil, iid: 690, merge_request_id: nil, source_sha: nil, target_sha: nil> ``` ### Output of checks This bug happens on GitLab.com Also happens on self-managed instances ### Possible fixes Not sure, but here's the method that's returning nil when we don't expect it to. [models/merge_request.rb#L281-283](https://gitlab.com/gitlab-org/gitlab/blob/33df3081195274e7eb6de1e4090a50a04b168844/app/models/merge_request.rb#L281-283) ### Workaround If you experience this same issue, then try this in the rails console (`sudo gitlab-rails console`): ```ruby project = Project.find_by_full_path('my-group/example-project') # you can find the iid of the MR by looking at the number at the end of the URL when viewing the MR mr = MergeRequest.find_by(project: project, iid: 154) mr.update_head_pipeline ```