new mounting of aufs images leaves unmounted stuff
Created by: udeved
After a second try on xfce-minimal in this case, which failed first try due to netkit-bsd not in repos, the second run produces this:
==> Removing [/build/buildiso/xfce-minimal/x86_64] ...
rm: cannot remove '/build/buildiso/xfce-minimal/x86_64/xfce-image': Device or resource busy
rm: cannot remove '/build/buildiso/xfce-minimal/x86_64/root-image': Device or resource busy