Steps:

1. Disable the setting display_fqdn_for_hosts in Satellite
2. Prepare dummy errata to apply on host
3. Navigate to Content > Content Types > Errata > Applicable/Installable
4. Select Errata and move to content hosts tab
5. Verify short-names are used and domain isn't appended

I check this used to work earlier on 6.14, and now short name isn't used here on errata page in stream/6.15