Revert r34619, r34622 and do it right. :)

Revert r34619, r34622 and do it right. :)

* $extensionsList is a local variable, not a global, so there is no actual register_globals danger -- just annoying E_NOTICE spam.
* Setting $extensionList won't help with warnings about unset $extensionsList ;)
* Cleaner to set it in the fallback case near where it's set otherwise, rather than at the top of the function far, far away from its use