Description of problem:

Issue filtering by source doesn't work if source is "None"

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

7.0.0-44

How reproducible:

100%

Steps to Reproduce:
1. Create an application and run analysis for it
2. Go to issues, make sure there is issue with source "None"
3. Filter in all issues list or in single app list by issue with source "None"

Actual results:

Table will be empty

Expected results:

Respective issues should be shown

Additional info:
Example of application used: book-server
One screenshot shows page without filters, second what happens if filter will be applied