Add link to open merge requests

app/views/projects/labels/_label.html.haml

@@ -2,6 +2,10 @@
   = render "shared/label_row", label: label
   .pull-right
+    %strong.append-right-20
+      = link_to_label(label, type: :merge_request) do
+        = pluralize label.open_merge_requests_count, 'open merge request'
+
     %strong.append-right-20
       = link_to_label(label) do
         = pluralize label.open_issues_count, 'open issue'