generate-app-headers.sh read APP with a plain grep -oP, so a script that
sets APP twice yielded both lines and the filename became
"almalinux
almalinux${var_version}vm". Three of those are in the tree
and they make main impossible to check out on Windows.
Nothing reads vm/headers: get_header fetches banners from the core
repo, which already carries clean almalinux, debian and ubuntu.