$ git clone -n https://src.fedoraproject.org/rpms/cosmic-files.git /var/lib/mock/f45-build-39736-751/root/chroot_tmpdir/scmroot/cosmic-files
Cloning into '/var/lib/mock/f45-build-39736-751/root/chroot_tmpdir/scmroot/cosmic-files'...
$ git fetch origin 890b569f7f7b963f3f336e49af21f93bbadb9b1f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/cosmic-files
 * [new ref]         890b569f7f7b963f3f336e49af21f93bbadb9b1f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 890b569 Update to 1.6.0