[libvirt] blockcopy qemu fail and libvirt

Hi, i'm use qemu 2.4.0 and libvirt 1.2.16 and try blockcopy to migrate vm disk virsh -c qemu+ssh://root@xxx/system blockcopy domain sda /dev/nbd2 --wait --pivot libvirt says: Successfully pivoted 2015-12-01 14:37:18.188+0000: 18288: info : libvirt version: 1.2.16 2015-12-01 14:37:18.188+0000: 18288: warning : virEventPollUpdateTimeout:268 : Ignoring invalid update timer -1 but virsh command returns zero exit code qemu blockcopy failed and target device contains zeroes. i see some qemu git commits about block/migration and block that can fix this isse, does qemu-devs confirm that this bug is fixed? Also libvirt devs - do you know about this libvirt issue (when virsh doing blockcopy and qemu process does not success complete blockcopy) ? -- Vasiliy Tolstov, e-mail: v.tolstov(a)selfip.ru