".xml-prev" files causing subsequent VM renames to fail

[mitchellh]

After I rename a VM, it is leaving ".xml-prev" files in the Machines folder, so even after I delete the VM entirely, the folder exists with only the ".xml-prev" files, causing subsequent renames to fail. Steps to reproduce:

1. Create a VM, lets say "foo"

2. Rename VM to "bar"

3. Delete the VM (just the machine and not the hard disk is fine)

4. Create a new VM, lets say "foo" again.

5. Attempt to rename to "bar" and get a VBOX_ERROR, since in the Machines folder, there is a "bar/foo.xml-prev"

[aeichner]

Please reopen if still relevant with a recent VirtualBox release.