Issue #3360762: Retrieve related MRs for the issue via the api-d7 endpoint

drupalorg/drupalorg.module

@@ -9981,6 +9981,11 @@ function drupalorg_restws_response_alter(&$response, $function, $formatName, $re
           _drupalorg_expand_comments($response['field_issue_credit']);
           _drupalorg_expand_comments($response['comments']);
         }
+
+        if (isset($parameters['related_mrs']) && $parameters['related_mrs'] === '1') {
+          // Include related merge requests links in the response.
+          _drupalorg_expand_related_mrs($response);          
+        }
         break;
     }
   }
@@ -10006,6 +10011,34 @@ function drupalorg_restws_response_alter(&$response, $function, $formatName, $re
   }
 }
 
+/**
+ * Includes related merge requests links.
+ */
+function _drupalorg_expand_related_mrs(&$response) {
+  if (empty($response['type']) || $response['type'] !== 'project_issue') {
+    return;
+  }
+
+  $wrapper = entity_metadata_wrapper('node', (object) $response);
+  $mrs_iids = [];
+  foreach (DrupalorgIssueFork::loadIssueForks($wrapper) as $issue_fork) {
+    $branches = $issue_fork->getBranches();
+    foreach ($branches as $branch) {
+      $mrs_iids = array_merge($mrs_iids, array_keys($branch->merge_requests));
+    }
+  }
+
+  $mrs_iids = array_unique($mrs_iids);
+  if (!empty($mrs_iids) && ($repository = versioncontrol_project_repository_load($response['field_project']['id']))) {
+    $repository_url = $repository->getUrlHandler()->getRepositoryViewUrl();
+    $mr_urls = [];
+    foreach ($mrs_iids as $mr_iid) {
+      $mr_urls[] = $repository_url . '/-/merge_requests/' . $mr_iid;
+    }
+    $response['related_mrs'] = $mr_urls;  
+  }
+}
+
 /**
  * Includes related information in the comments.
  */