Description of problem:

There's no value for Operating system in VM's Guest Info tab

engine=# select vm_guid,guestos_arch,guestos_codename,guestos_distribution,guestos_kernel_version,guestos_type,guestos_version from vm_dynamic where vm_guid = '77447af6-731c-431c-95c3-68245d81aeaf';
-[ RECORD 1 ]----------+-------------------------------------
vm_guid                | 77447af6-731c-431c-95c3-68245d81aeaf
guestos_arch           | 1
guestos_codename       | Win 8
guestos_distribution   | 
guestos_kernel_version | 
guestos_type           | Windows
guestos_version        | 6.2


        guestOsInfo = {'kernel': '', 'arch': 'x86_64', 'version': '6.2', 'distribution': '', 'type': 'windows', 'codename': 'Win 8'}
        username = user@jb-w81x64
        guestName = JB-W81X64


Version-Release number of selected component (if applicable):
rhevm-3.6.1-0.2.el6.noarch / 3.6.2 WGT iso

How reproducible:
100%

Steps to Reproduce:
1. have windows with 3.6.2 WGT and see what's value for Operating system in
   Guest Info subtab
2.
3.

Actual results:
Operating system value is empty

Expected results:
OS value should be reported as DB has it

Additional info: