Quick tip: Joomla white page and rsync

I recently worked on a joomla page. And since I love rsync, I made myself a build/sync script to update the page on the test server. The command was similar to the following:
$ rsync --exclude-from=build/rsync.exclude ...
The contents of rsyn.exclude contained:
cache/*
logs/*
tmp/*
...
But when I first ran the script, all I got was a white blank page. No apache errors, no PHP errors. Strange. Then it hit me. Joomla has some cache classes within cache/ directories. So removing the cache/* from rsync.exclude and running the script again made it work.
Of course then there is another matter of clearing the cache, but it is beyond the scope of this quick tip.