Today's discovery is that if the "mv" command can't simply rename a directory due to permissions, then it'll copy the directory structure. Then attempt to delete the old directory structure, fail because of the aforementioned permissions, and spew umpteen bajillion lines of error messages on the console.
Now, a sensible program would have just said that the file permissions didn't permit renaming and stopped there.
Sigh. Now to unpick the mess and check if it did actually copy everything or not.