Prevent mutation assignee widget without changes

Prevent firing mutation when editing and exiting assignee widget without changes

app/assets/javascripts/sidebar/components/assignees/sidebar_assignees_widget.vue

@@ -175,8 +175,10 @@ export default {
       this.updateAssignees([this.currentUser.username]);
     },
     saveAssignees() {
-      this.isDirty = false;
-      this.updateAssignees(this.selected.map(({ username }) => username));
+      if (this.isDirty) {
+        this.isDirty = false;
+        this.updateAssignees(this.selected.map(({ username }) => username));
+      }
       this.$el.dispatchEvent(hideDropdownEvent);
     },
     collapseWidget() {

spec/frontend/sidebar/components/assignees/sidebar_assignees_widget_spec.js

@@ -208,6 +208,22 @@ describe('Sidebar assignees widget', () => {
       ]);
     });
 
+    it('does not trigger mutation or fire event  when editing and exiting without making changes', async () => {
+      createComponent();
+
+      await waitForPromises();
+
+      findEditableItem().vm.$emit('open');
+
+      await waitForPromises();
+
+      findEditableItem().vm.$emit('close');
+
+      expect(findEditableItem().props('isDirty')).toBe(false);
+      expect(updateIssueAssigneesMutationSuccess).toHaveBeenCalledTimes(0);
+      expect(wrapper.emitted('assignees-updated')).toBe(undefined);
+    });
+
     describe('when expanded', () => {
       beforeEach(async () => {
         createComponent();