Patch keeps failing "File naming" test but has nothing to do with files!

Issue Summary

Hi,

Perhaps I'm fundamentally misunderstanding something here, but I couldn't find any help elsewhere and I took a look at file.test in modules/simpletest/tests and it doesn't seem relevant to my patch, so I don't know why it's failing.

Issue is here:
http://drupal.org/node/314756#comment-1286788

Test results here:
http://testing.drupal.org/pifr/file/1/drupal_set_message_0.diff

If someone could take a look and tell me what's going on, I'd appreciate it. Beats the hell out of me. =(

Thanks!