Stop git zombie creation during force push check

CHANGELOG

@@ -20,7 +20,7 @@ v 7.8.0
   - 
   - 
   - 
-  - 
+  - Stop git zombie creation during force push check
   - 
   - 
   - 

lib/gitlab/force_push_check.rb

@@ -4,7 +4,7 @@ module Gitlab
       return false if project.empty_repo?
 
       if oldrev != Gitlab::Git::BLANK_SHA && newrev != Gitlab::Git::BLANK_SHA
-        missed_refs = IO.popen(%W(git --git-dir=#{project.repository.path_to_repo} rev-list #{oldrev} ^#{newrev})).read
+        missed_refs, _ = Gitlab::Popen.popen(%W(git --git-dir=#{project.repository.path_to_repo} rev-list #{oldrev} ^#{newrev}))
         missed_refs.split("\n").size > 0
       else
         false