Magento installation fails with 'PHP Extensions "0" must be loaded' on PHP 5.4

When trying to execute the installDb step of the install process, Magento complains that 'PHP Extensions "0" must be loaded'. Reproduced with SimpleXML revision `5514f0fc897197ca9a199fb93b8b5d9135ad711a`.

![Screen Shot 2013-03-08 at 8 39 32 PM](https://f.cloud.github.com/assets/1423851/239277/60eee7e8-8873-11e2-97fe-84b1faed9373.png)