litmus move_coll test sometimes fails due to locking

[provokateurin]

Fails with 500:

<?xml version="1.0" encoding="utf-8"?>
<d:error xmlns:d="DAV:" xmlns:s="http://sabredav.org/ns">
  <s:exception>OCP\Lock\LockedException</s:exception>
  <s:message>"dst1" is locked</s:message>
</d:error>

Not sure if we can do anything since there should be no lock at all.