Cloned from https://bugzilla.redhat.com/show_bug.cgi?id=1582210

Description of problem:
In a Hosts -> Create Host dialogue, when RHEV selected as a provider, listing OS images causes traceback when there are no images added to the Compute Resource.

Version-Release number of selected component (if applicable):
Sat6.4 snap4

How reproducible:
Deterministic

Steps to Reproduce:
0. Have some CR and OS with image with that OS in CR
1. Hosts -> Create Host
2. Select Org etc. as necessary
3. Go to Operating System tab
4. Select arch, OS
5. # foreman-tail
6. Select Image-Based

Actual results:
Traceback in production.log

Expected results:
No traceback

Additional info:
I haven't noticed any other problems caused by this. Traceback attached.