etherpad-lite doesn't deploy

2013-04-09 20:27:00,125: hook.executor@DEBUG: Running hook: /var/lib/juju/units/etherpad-lite-0/charm/hooks/config-changed
2013-04-09 20:27:00,271: unit.hook.api@INFO: Updating ...
2013-04-09 20:27:00,328: hook.output@INFO: Previous HEAD position was cfb58a8... Merge git://github.com/Gared/etherpad-lite

2013-04-09 20:27:00,330: hook.output@INFO: Switched to branch 'master'

2013-04-09 20:27:02,093: hook.output@INFO: Already up-to-date.

2013-04-09 20:27:02,264: hook.output@INFO: error: The following untracked working tree files would be overwritten by checkout:
        static/js/prefixfree.js
Please move or remove them before you can switch branches.
Aborting

2013-04-09 20:27:02,264: hook.output@DEBUG: hook config-changed exited, exit code Traceback (most recent call last):
Failure: juju.errors.CharmInvocationError: Error processing '/var/lib/juju/units/etherpad-lite-0/charm/hooks/config-changed': exit code 1.
.
2013-04-09 20:27:02,264: hook.executor@DEBUG: Hook error: /var/lib/juju/units/etherpad-lite-0/charm/hooks/config-changed Error processing '/var/lib/juju/units/etherpad-lite-0/charm/hooks/config-changed': exit code 1.
2013-04-09 20:27:02,265: statemachine@DEBUG: unitworkflowstate: executing error transition error_configure, Error processing '/var/lib/juju/units/etherpad-lite-0/charm/hooks/config-changed': exit code 1.

Full log attached.