svnsync problems

I have a little cron job that syncs two svn repos. It runs every ten minutes. For some reason it stopped working so I killed the job. Now when I try to manually run the job, I get:

Failed to get lock on destination repos, currently held by...

Great, the sync is broken!
Here is how to clear it up. Use the following command to remove the lock:

svn propdel --revprop -r0 svn:sync-lock file:///path/to/the/repository

This is the sync script:

#!/bin/sh
svnsync synchronize file:///path/to/the/repository --username svnuser --password svnpassword