[Mediawiki-l] Missing wfStrencode() - MediaWIki 1.9

[Stephen Collins]

I have a couple of extensions I'm using (rss and a custom one) where  
I'm getting the following error:

Fatal error: Call to undefined function wfStrencode() in /home/3698/ 
domains/swc/html/smsp1/extensions/rss.php on line 206

This is using MediaWiki 1.9 from SVN.  Looks like it may be broken  
somewhere (or, alternatively and more likely, I've done something  
stupid).

It works just fine in my MediaWiki 1.8.2 install...

Any words of advice from the more knowledgeable much appreciated.

Steve