I just submitted new version to Bodhi.
From the release notes:
https://github.com/rpm-software-management/mock/wiki/Release-Notes-1.4.4
* Fedora 27 configs have been added.
* /etc/dnf/dnf.conf is used instead of /etc/dnf.conf
* /etc/dnf/dnf.conf is populated even when yum is used
* Rename group inside of chroot from mockbuild to mock - this will allow you to install
mock inside of mock' chroot.
Mirek