Hi,
   libvirt 0.7.3 adds the VIR_MIGRATE_PERSIST_DEST, VIR_MIGRATE_UNDEFINE_SOURCE flags in migration, which are very useful in our product. Unfortunately, we use libvirt 0.6.3.20, which is the default in RHEL 5.4. No such advanced migration feature in this version.
   I backported it for 0.6.3.20, in the attached patch.  Do you think it's possible to be merged into 0.6.3.20?:)