Default issue tracker fix for creating default issue service.

app/models/project.rb

@@ -321,7 +321,7 @@ class Project < ActiveRecord::Base
   end
 
   def default_issue_tracker
-    gitlab_issue_tracker_service ||= create_gitlab_issue_tracker_service
+    gitlab_issue_tracker_service || create_gitlab_issue_tracker_service
   end
 
   def issues_tracker