I added this downstream in Tremulous a while ago and it's been useful to both users and people who help users troubleshoot, so I thought I would put it here to see if you guys want it.

Adds a command
/which <filename>
that prints what path that file is loaded from.

The reasoning is that things load from basepath, homepath, inside pk3s, out of pk3s, etc. with different override priorities, and figuring out exactly where you're loading a problematic item from (or why you're not loading something you want) can be a bit troublesome for people who aren't intimately familiar with how the q3 filesystem works. In Tremulous the problem was always that people tried to install mods but wouldn't put them in the correct places. 

This patch creates a command to quickly answer the "which" question for a given file/folder and adds an automatic call to it when vms are loaded to state where from.

While I've cleaned it up a bit and trivially ported it from tremulous to ioq3, the original patch and perhaps the idea are attributed to Amanieu d'Antras.