ensure volumes are free'd if there are no errors
ensure volumes are free'd if there are no errors

Make sure to only then free volumes if there are no errors.

This fixes #151.

Signed-off-by: Thomas Hipp <ba262c2d62f6fd76f236e5802148840e86e9b719@suse.de>

dmacvicar/terraform-provider-libvirt,deasmi/terraform-provider-libvirt,deasmi/terraform-provider-libvirt,dmacvicar/terraform-provider-libvirt,dmacvicar/terraform-provider-libvirt,deasmi/terraform-provider-libvirt