Mark Windows 10 as a rolling release
I just found, that current virt-manager marks all OS release as EOL, if they don't have an EOL and didn't had a release since five years. This just removed Windows 10 from the default list of supported OS releases.
So this simply marks Windows 10 as a rolling release (which is not true, since all annually, non-enterprise or non-edu feature updates are (currently) supported for 18 months, notwithstanding LTS[BC] releases).
This is the info I got from https://support.microsoft.com/en-us/help/13853/windows-lifecycle-fact-sheet