Fix timeout error when preparing git graph.

app/models/repository.rb

@@ -134,7 +134,7 @@ class Repository
 
   def graph_log
     Rails.cache.fetch(cache_key(:graph_log)) do
-      stats = Gitlab::Git::GitStats.new(raw, root_ref)
+      stats = Gitlab::Git::GitStats.new(raw, root_ref, Gitlab.config.git.timeout)
       stats.parsed_log
     end
   end