3.0.x vs. 3.1.x

It looks like we have a regression:

http://pecl.php.net/bugs/bug.php?id=13505

The largest change from 3.0.16 was the expunge callback stuff.  Gopal 
has new code for 3.1.0 that will make cache expunges much easier and 
this code will need to change completely.  And since we don't actually 
use it in 3.0.x, I think we should just pull it from the 3.0 tree and 
see if that fixes the MediaWiki issue.

We should also fix:

http://pecl.php.net/bugs/bug.php?id=13504

Probably means we need a 3.0.18 sometime soon.

-Rasmus