Description of problem:

When setupNetwork command is invoked, the engine calculates the differences between the latest reported configuration to the new configuration requested by the user.

Only the modified interfaces/networks are sent to VDSM.

When no changes are done in setupNetworks, the engine sends an empty command (no interfaces nor networks are specified) which makes the call to VDSM redundant.

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


How reproducible:
always

Steps to Reproduce:
1. Run setupNetwork command.
2. Rerun setupNetwork command with no changes since previous command.
  
Actual results:
The engine sends an empty setupNetwork command to VDSM, which appears on VDSM logs setupNetwork command without any parameter:
 
Thread-238905::DEBUG::2013-01-21
13:35:04,830::BindingXMLRPC::894::vds::(wrapper) client
[10.65.210.91]::call setupNetworks with ({}, {}, {'connectivityCheck':
'true', 'connectivityTimeout': 120}) {} flowID [1967da34]

Expected results:
The call to VDSM should be spared.

Additional info: