civicrm/civicrm-core — pull request #2529 by xurizaemon (2014-02-16 22:17:03+00:00)
Title: CRM-14210. Use get_headers() not file_get_contents()

I understood that file_get_contents() returned FALSE on failure, but a couple of sites reported that the check was passing even when the file wasn't accessible (checked via apache logs and HTTP response).

So, use get_headers() instead of file_get_contents(), then look for a 200 in $headers[0], and warn if we see that.