Fix issue when developers are able to push to protected branch

When that branch contain a '/' in the branch name.
Fix for git over HTTP

lib/gitlab/backend/grack_auth.rb

@@ -110,7 +110,7 @@ module Grack
 
       # Need to reset seek point
       @request.body.rewind
-      /refs\/heads\/([\w\.-]+)/n.match(input.force_encoding('ascii-8bit')).to_a.last
+      /refs\/heads\/([\/\w\.-]+)/n.match(input.force_encoding('ascii-8bit')).to_a.last
     end
   end
 end