Description of problem:

At present the FlowID provided from the engine is not passed to destination host during a migration. 

For example, given a FlowID of 74b90f3b and two sets of logs from the src and dst I can't easily correlate the migration with the following :

# xzgrep 74b90f3b */var/log/vdsm/vdsm.log*
i-mpweb2-2013030713401362660024/var/log/vdsm/vdsm.log.1.xz:Thread-890403::DEBUG::2013-03-07 12:07:40,020::BindingXMLRPC::894::vds::(wrapper) client [10.204.176.51]::call vmMigrate with ({'src': '10.204.125.22', 'dst': '10.204.125.21:54321', 'vmId': '1234', 'method': 'online'},) {} flowID [74b90f3b]

Version-Release number of selected component (if applicable):
4.10.2-1.6

How reproducible:
Migrate guest, attempt to correlate src and dst vdsm logs with FlowID.

Actual results:
FlowID not passed to dst host.

Expected results:
FlowID passed to dst host allowing limited correlation of migration.

Additional info:
This is just a nice to have for failures during mass migrations.