Merge branch 'defect/mr-bug-fixes' into 'master'

Fix for: check for highlighted_diff_lines iterates over parallel_diff_lines; parallel left/right duplicates property

See merge request gitlab-org/gitlab!21573

app/assets/javascripts/diffs/components/diff_line_gutter_content.vue

@@ -72,7 +72,7 @@ export default {
     lineCode() {
       return (
         this.line.line_code ||
-        (this.line.left && this.line.line.left.line_code) ||
+        (this.line.left && this.line.left.line_code) ||
         (this.line.right && this.line.right.line_code)
       );
     },

app/assets/javascripts/diffs/store/utils.js

@@ -498,7 +498,7 @@ export const allDiscussionWrappersExpanded = diff => {
       }
     });
   } else if (diff.highlighted_diff_lines) {
-    diff.parallel_diff_lines.forEach(line => {
+    diff.highlighted_diff_lines.forEach(line => {
       if (line.discussions.length) {
         discussionsExpandedArray.push(line.discussionsExpanded);
       }