libvirt users - Nov 2014 - python migrateSetMaxSpeed not taking effect

Hi,

I am writing a simple python script for migrating vm's based on zfs
zvol's.
Either I am doing something wrong or python migrateSetMaxSpeed not taking
effect: no mater what value I specify (except for 0), I end up with 10
Mib/s migration speed. The code is:

def virt_migrate(domain):
    conn = libvirt.open('qemu:///system')
    domain_obj = conn.lookupByName(domain)
    dst='qemu+ssh://root@%s/system' % args.remote
    domain_obj.migrateSetMaxSpeed(40,0)
    new_dom = domain_obj.migrateToURI(dst,libvirt.VIR_MIGRATE_LIVE |
libvirt.VIR_MIGRATE_PEER2PEER | libvirt.VIR_MIGRATE_NON_SHARED_INC |
libvirt.VIR_MIGRATE_PERSIST_DEST | libvirt.VIR_MIGRATE_UNDEFINE_SOURCE,
None, 0)
    conn.close()

Also tried to specify bandwidth at migrateToUri- I still get 10 mib/s at
any value...

Thanks in advance!