$ git clone -n https://src.fedoraproject.org/rpms/gnome-contacts.git /var/lib/mock/f42-build-3329555-41426/root/chroot_tmpdir/scmroot/gnome-contacts
Cloning into '/var/lib/mock/f42-build-3329555-41426/root/chroot_tmpdir/scmroot/gnome-contacts'...
$ git fetch origin b3539f69ec2e21a0731e260cd76a09f48d91941e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-contacts
 * [new ref]         b3539f69ec2e21a0731e260cd76a09f48d91941e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b3539f6 Update to 48.beta