Removes label from previous list

When dragging an issue to a list that it already exists in it was previously not removing the label for the list it was moving from. This changes that to make that API call.

Closes #28484

app/assets/javascripts/boards/models/list.js.es6

@@ -123,13 +123,17 @@ class List {
 
       if (listFrom) {
         this.issuesSize += 1;
+        this.updateIssueLabel(issue, listFrom);
+      }
+    }
+  }
+
+  updateIssueLabel(issue, listFrom) {
     gl.boardService.moveIssue(issue.id, listFrom.id, this.id)
       .then(() => {
         listFrom.getIssues(false);
       });
   }
-    }
-  }
 
   findIssue (id) {
     return this.issues.filter(issue => issue.id === id)[0];

app/assets/javascripts/boards/stores/boards_store.js.es6

@@ -92,9 +92,12 @@
       const issueLists = issue.getLists();
       const listLabels = issueLists.map(listIssue => listIssue.label);
 
-      // Add to new lists issues if it doesn't already exist
       if (!issueTo) {
+        // Add to new lists issues if it doesn't already exist
         listTo.addIssue(issue, listFrom, newIndex);
+      } else {
+        listTo.updateIssueLabel(issue, listFrom);
+        issueTo.removeLabel(listFrom.label);
       }
 
       if (listTo.type === 'done') {

changelogs/unreleased/moving-issue-with-two-list-labels.yml

+---
+title: Removes label when moving issue to another list that it is currently in
+merge_request:
+author:

spec/javascripts/boards/list_spec.js.es6

@@ -3,7 +3,9 @@
 /* global boardsMockInterceptor */
 /* global BoardService */
 /* global List */
+/* global ListIssue */
 /* global listObj */
+/* global listObjDuplicate */
 
 require('~/lib/utils/url_utility');
 require('~/boards/models/issue');
@@ -84,4 +86,23 @@ describe('List model', () => {
       done();
     }, 0);
   });
+
+  it('sends service request to update issue label', () => {
+    const listDup = new List(listObjDuplicate);
+    const issue = new ListIssue({
+      title: 'Testing',
+      iid: 1,
+      confidential: false,
+      labels: [list.label, listDup.label]
+    });
+
+    list.issues.push(issue);
+    listDup.issues.push(issue);
+
+    spyOn(gl.boardService, 'moveIssue').and.callThrough();
+
+    listDup.updateIssueLabel(list, issue);
+
+    expect(gl.boardService.moveIssue).toHaveBeenCalledWith(issue.id, list.id, listDup.id);
+  });
 });