qvm-remove: undefine libvirt domain even when not removing files

Fixes QubesOS/qubes-issues#2112

qvm-tools/qvm-remove

@@ -79,6 +79,10 @@ def main():
             exit (1)
 
     try:
+        if options.remove_from_db_only:
+            # normally it is done by vm.remove_from_disk(), but it isn't
+            # called in this case
+            vm.libvirt_domain.undefine()
         if vm.installed_by_rpm:
             if options.verbose:
                 print >> sys.stderr, "--> VM installed by RPM, leaving all the files on disk"