The code that creates the directories are the exact same code that copies files.
So this is very strange.
Any chance the location of tmp and deployment is on two different file systems ?
Then the mv function could fail (really annoying bug because Java can't tell us if paths are on different filesystems)
To know if this is the case go to deployment tab and set the "Temporary deployment folder" to a temp folder that is on the same filesystem as where your are deploying to.