Init MR Popovers on system note mounted

All `renderGFM()` calls are finished before the system note is mounted
so this MR inits the popover for each system note, and only the elements
in the system note

app/assets/javascripts/vue_shared/components/notes/system_note.vue

@@ -22,6 +22,7 @@ import noteHeader from '~/notes/components/note_header.vue';
 import Icon from '~/vue_shared/components/icon.vue';
 import TimelineEntryItem from './timeline_entry_item.vue';
 import { spriteIcon } from '../../../lib/utils/common_utils';
+import initMRPopovers from '~/mr_popover/';
 
 const MAX_VISIBLE_COMMIT_LIST_COUNT = 3;
 
@@ -71,6 +72,9 @@ export default {
       );
     },
   },
+  mounted() {
+    initMRPopovers(this.$el.querySelectorAll('.gfm-merge_request'));
+  },
 };
 </script>
 

changelogs/unreleased/60855-mr-popover-is-not-attached-in-system-notes.yml

+---
+title: Fix bug where system note MR has no popover
+merge_request: 27747
+author:
+type: fixed

spec/frontend/vue_shared/components/notes/system_note_spec.js

 import Vue from 'vue';
 import issueSystemNote from '~/vue_shared/components/notes/system_note.vue';
 import createStore from '~/notes/stores';
+import initMRPopovers from '~/mr_popover/index';
+
+jest.mock('~/mr_popover/index', () => jest.fn());
 
 describe('system note component', () => {
   let vm;
@@ -56,4 +59,8 @@ describe('system note component', () => {
   it('removes wrapping paragraph from note HTML', () => {
     expect(vm.$el.querySelector('.system-note-message').innerHTML).toEqual('<span>closed</span>');
   });
+
+  it('should initMRPopovers onMount', () => {
+    expect(initMRPopovers).toHaveBeenCalled();
+  });
 });