Internal server error when searching

When searching a repository, searching e.g. after getattr(, i get a instant 500 error message.

if i search for getattr() it works.

any search with a "(" OR ")" will cause the 500 error. Tested in both my private gitlab-ce install and on gitlab.com.

example URL for reproduction: https://gitlab.com/search?utf8=%E2%9C%93&search=getattr%28&group_id=&project_id=13083&search_code=true&repository_ref=master (and sorry for the very low detailed bug-report, in a hurry :-( )