Prevent same branch in MR seeds

app/views/merge_requests/show/_commits.html.haml

@@ -22,9 +22,9 @@
             = render "commits/commit", commit: commit
 - else
-  %h5
+  %h4.nothing_here_message
     Nothing to merge from
-    %span.label #{@merge_request.source_branch}
+    %span.label-branch #{@merge_request.source_branch}
     to
-    %span.label #{@merge_request.target_branch}
+    %span.label-branch #{@merge_request.target_branch}
   %br

db/fixtures/development/10_merge_requests.rb

@@ -14,6 +14,8 @@ Gitlab::Seeder.quiet do
     branches = project.repository.branch_names.sample(2)
+    next if branches.uniq.size < 2
+
     user_id = user.id
     MergeRequestObserver.current_user = user
     MergeRequest.seed(:id, [{