$ git clone -n https://src.fedoraproject.org/rpms/emacs.git /var/lib/mock/f42-build-side-1-3555999-46656/root/chroot_tmpdir/scmroot/emacs
Cloning into '/var/lib/mock/f42-build-side-1-3555999-46656/root/chroot_tmpdir/scmroot/emacs'...
$ git fetch origin e6a65ae22b72f417b3de30db958007bc3c1a7502:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/emacs
 * [new ref]         e6a65ae22b72f417b3de30db958007bc3c1a7502 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e6a65ae Package emacsclient should conflict with the last F40 emacs-common.