Description of problem:
A VM migrated from RHEL6.6 host to RHEL7.0 host can't be powered off.

1. rhel66 poweroff ok
2. rhel70 poweroff ok
3. rhel66->rhel7 migrated, poweroff ko

~~~
Thread-314::ERROR::2014-10-17 15:16:11,047::__init__::491::jsonrpc.JsonRpcServer::(_serveRequest) Internal server error
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/yajsonrpc/__init__.py", line 486, in _serveRequest
    res = method(**params)
  File "/usr/share/vdsm/rpc/Bridge.py", line 266, in _dynamicMethod
    result = fn(*methodArgs)
  File "/usr/share/vdsm/API.py", line 338, in destroy
    res = v.destroy()
  File "/usr/share/vdsm/virt/vm.py", line 4921, in destroy
    response = self.doDestroy()
  File "/usr/share/vdsm/virt/vm.py", line 4938, in doDestroy
    return self.releaseVm()
  File "/usr/share/vdsm/virt/vm.py", line 4839, in releaseVm
    supervdsm.getProxy().removeFs(drive.path)
  File "/usr/share/vdsm/supervdsm.py", line 50, in __call__
    return callMethod()
  File "/usr/share/vdsm/supervdsm.py", line 48, in <lambda>
    **kwargs)
  File "<string>", line 2, in removeFs
  File "/usr/lib64/python2.7/multiprocessing/managers.py", line 773, in _callmethod
    raise convert_to_error(kind, result)
Exception: Cannot remove Fs that does not exists in: /var/run/vdsm/payload
~~~

plus journalctl -u libvirtd --no-paged

~~~
Oct 17 15:15:30 dell-r210ii-04.rhev.lab.eng.brq.redhat.com libvirtd[18347]: Failed to open file '/var/run/vdsm/payload/fbec56ea-3f03-4f0b-a33e-598e24725350.b77126d9f4...irectory
Oct 17 15:15:31 dell-r210ii-04.rhev.lab.eng.brq.redhat.com libvirtd[18347]: This thread seems to be the async job owner; entering monitor without asking for a nested ...angerous
~~~

4. rhel70 -> rhel66 migration-blocked - migration doesn't work

Version-Release number of selected component (if applicable):
vdsm-4.16.7-1.el7.x86_64
libvirt-daemon-1.1.1-29.el7_0.3.x86_64
qemu-kvm-rhev-1.5.3-60.el7_0.10.x86_64

How reproducible:
100%

Steps to Reproduce:
1. have rhel66 and rhel70 hosts
2. create __NEW__ vm and start it on rhel66 host
3. migrate this VM to rhel70 host
4. poweroff the VM

Actual results:
failed to power off the VM

Expected results:
should work

Additional info:
see above that "static" (ie. powering off not migrated VMs work ok on rhel70 host)

important: when the VM is started on rhel70, then powered off, then started on rhel66 and migrated successfully to rhel70 host and then powered off,... it works! thyus it is '__NEW__' in 2nd steps to reproduce this issue