Description of problem:
Migration fails with -dname option when guest agent is specified in guest XML.
The migrated guest XML on target machine is not updated to use new guest name specified by -dname.

Version-Release number of selected component (if applicable):
libvirt-1.2.17-13.el7_2.2.x86_64
qemu-kvm-rhev-2.3.0-31.el7.x86_64
kernel-3.10.0-320.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Start a guest.
# virsh list --all
 Id    Name                           State
----------------------------------------------------
 30    avocado-vt-vm1                 running

2. Check the dumpxml of the guest.
   <channel type='unix'>
      <source mode='bind' path='/var/lib/libvirt/qemu/channel/target/domain-avocado-vt-vm1/org.qemu.guest_agent.0'/>
      <target type='virtio' name='org.qemu.guest_agent.0' state='connected'/>
      <alias name='channel0'/>
      <address type='virtio-serial' controller='0' bus='0' port='1'/>
    </channel>

3. Check the file.
# ll /var/lib/libvirt/qemu/channel/target/domain-avocado-vt-vm1/
total 0
srwxrwxr-x. 1 qemu qemu 0 Dec 29 16:59 org.qemu.guest_agent.0

4. Do migration
# virsh migrate --live --domain avocado-vt-vm1 --desturi qemu+ssh://10.66.4.167/system --dname not_exist_domain
root.4.167's password:
error: internal error: process exited while connecting to monitor: 2015-12-29T08:59:07.318646Z qemu-kvm: -chardev socket,id=charchannel0,path=/var/lib/libvirt/qemu/channel/target/domain-avocado-vt-vm1/org.qemu.guest_agent.0,server,nowait: Failed to bind socket to /var/lib/libvirt/qemu/channel/target/domain-avocado-vt-vm1/org.qemu.guest_agent.0: No such file or directory

5. Check on the target machine (10.66.4.167/), and no guest exists.

Actual result:
See step 4.
The migration fails.


Expected result:
The migration should succeed and the guest named 'not_exist_domain' should be running on target machine.

Additional information:
Debug information on target machine.
# cat /var/log/libvirt/qemu/not_exist_domain.log
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin QEMU_AUDIO_DRV=none /usr/libexec/qemu-kvm -name not_exist_domain -S -machine pc-i440fx-rhel7.2.0,accel=kvm,usb=off -cpu SandyBridge -m 1024 -realtime mlock=off -smp 2,sockets=2,cores=1,threads=1 -uuid 5d7c2231-5f46-4b94-bbd8-e46f245e1402 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/domain-not_exist_domain/monitor.sock,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc,driftfix=slew -global kvm-pit.lost_tick_policy=discard -no-hpet -no-shutdown -global PIIX4_PM.disable_s3=1 -global PIIX4_PM.disable_s4=1 -boot strict=on -device ich9-usb-ehci1,id=usb,bus=pci.0,addr=0x5.0x7 -device ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,addr=0x5 -device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pci.0,addr=0x5.0x1 -device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.0,addr=0x5.0x2 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x4 -drive file=/usr/share/avocado/data/avocado-vt/images/jeos-19-64.qcow2,if=none,id=drive-virtio-disk0,format=qcow2,cache=none -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x6,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -netdev tap,fd=23,id=hostnet0,vhost=on,vhostfd=24 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:52:53:54,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev socket,id=charchannel0,path=/var/lib/libvirt/qemu/channel/target/domain-avocado-vt-vm1/org.qemu.guest_agent.0,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.qemu.guest_agent.0 -device usb-tablet,id=input0 -vnc 127.0.0.1:0 -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 -incoming tcp:[::]:49152 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x7 -msg timestamp=on

*** This is wrong parameter in the command line.
-chardev socket,id=charchannel0,path=/var/lib/libvirt/qemu/channel/target/domain-avocado-vt-vm1/org.qemu.guest_agent.0