Issue: The original ebuild creates files and folders which are not required, e.g. if you use fcron with USE flag  -system-crontab .

The ebuild name is cronbase-1.ebuild, because at least the fcron-3.2.1-r1::gentoo ebuild has a dependency:  >=sys-process/cronbase-0.3.2) M[package.mask] . Thus we have to put into  /etc/portage/package.mask/qrtools :

sys-process/cronbase::gentoo

As it's in an overlay it will overlay the same version in Gentoo portage - if it exists. All over versions are masked.