Description of problem:
When attaching host USB device to VM, the VM failed to run.
Issue occurred on AMD and Intel hosts and, RHEL7 and windows 2012 VMs and different USB devices (DOK and Keyboard).
Same VMs run properly when detaching host USB device.

Observing engine.log shows the next ERROR:

2015-09-08 16:41:35,933 ERROR [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (ForkJoinPool-1-worker-5) [] Correlation ID: null, Call 
Stack: null, Custom Event ID: -1, Message: VM rhel7_amd is down with error. Exit message: local variable 'device' referenced before assignment.
2015-09-08 16:41:35,934 INFO  [org.ovirt.engine.core.vdsbroker.VmAnalyzer] (ForkJoinPool-1-worker-5) [] Running on vds during rerun failed vm: '4e47202c-f55a
-47c2-ae8f-2d0567c266b9'

Version-Release number of selected component (if applicable):
rhevm-3.6.0-0.13.master.el6
sanlock-3.2.4-1.el7.x86_64
qemu-kvm-rhev-2.3.0-22.el7.x86_64
vdsm-4.17.5-1.el7ev.noarch
libvirt-client-1.2.17-5.el7.x86_64

How reproducible:
Consistently

Steps to Reproduce:
1. Attach host USB device to VM.
2. Run VM.
3.

Actual results:
VM failed to run and return to "down" state.
Next audit log displayed at webadmin UI: 
VM win2012_intel is down with error. Exit message: local variable 'device' referenced before assignment.

Expected results:
VM should run wuth USB device attached.

Additional info:
engine and vdsm logs attached.
issues time:
AMD host with RHEL7 VM with USB DOK attached: 2015-09-08 16:41:32
Intel host with windows 2012 VM and USB keyboard attached: 2015-09-08 16:48:52