Description of problem:
can't create LSM snapshot

Version-Release number of selected component (if applicable):
3.3 is5

How reproducible:
100%

Steps to Reproduce:
1. on iscsi storage, start a vm with one disk on two hosts (my vm was running on the hsm)
2. live migrate the vms disk

Actual results:
failed to create snapshot

Expected results:
should work

Additional info:
================
Thread-4160::ERROR::2013-07-16 18:30:23,404::BindingXMLRPC::954::vds::(wrapper) unexpected error
Traceback (most recent call last):
  File "/usr/share/vdsm/BindingXMLRPC.py", line 940, in wrapper
    res = f(*args, **kwargs)
TypeError: vmSnapshot() takes exactly 3 arguments (4 given)