Description of problem:
In template list, edit the windows 10 template's boot source reference and wait for enough time, it shows no boot source for this template.

Version-Release number of selected component (if applicable):
4.12

How reproducible:
100%

Steps to Reproduce:
1. select windows 10 template
2. edit the template's boot source reference
3. wait for enough time

Actual results:
it shows no boot source for this template

Expected results:
it shows source available after wait for some time

Additional info:
it does not happen in 4.11