Comment 1 for bug 1575007

Looks like it was an inadvertent omission in the upstream libvirt patch: "The refactoring in commit a26669d silently ignored the dxml
parameter of virDomainMigrateToURI2."[1]

Lee Yarwood has pointed out on #openstack-nova that there are past instances where we've blacklisted specific buggy libvirt versions. E.g. take a look here[2]. So something similar could be done in this case, too.

[1] https://www.redhat.com/archives/libvir-list/2016-January/msg00058.html
[2] https://github.com/openstack/nova/blob/master/nova/virt/libvirt/driver.py#L5229,L5238