env vars in HEAD/proc_open() issue?

Hi all, While merging ext/phar to HEAD, I found that environmental variables set in tests using the --ENV-- section fail to make it as far as the SAPI. Same with any other env var setting (e.g. my new '-x' parameter to run-tests.php fails too). Over 100 'frontcontroller' and similar tests in phar fail in HEAD due to this (at least, I _hope_ just due to this!), so reproducing the problem is easy enough. I'd report it as a bug if I knew roughly where the problem lay, but it could be down to any of several culprits. That said, everything seems to be working right up to the point where proc_open() is called in system_with_timeout(). Can anyone on a different platform please confirm/give further clues? Thanks, - Steph