The gitlab pre-receive hook expects the call to exec to return 1

when a user has access. Doing an exit 0 effectively ended the
thread. No code would be executed after the call to exec.

This changes fixes the problem for the pre-receive hooks but you want
to check that GitlabAccess.exec is not used elsewhere. A quick
grep of the code seems to indicate this is not the case

lib/gitlab_access.rb

@@ -18,7 +18,7 @@ class GitlabAccess
 
   def exec
     if api.allowed?('git-receive-pack', @repo_name, @actor, @changes)
-      exit 0
+      return 1
     else
       # reset GL_ID env since we stop git push here
       ENV['GL_ID'] = nil