$ git clone -n https://src.fedoraproject.org/rpms/R-lifecycle.git /var/lib/mock/f42-build-side-1-3501670-45976/root/chroot_tmpdir/scmroot/R-lifecycle
Cloning into '/var/lib/mock/f42-build-side-1-3501670-45976/root/chroot_tmpdir/scmroot/R-lifecycle'...
$ git fetch origin b6d8eb9c25303c2134802a924c5356cf5afc8ab7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-lifecycle
 * [new ref]         b6d8eb9c25303c2134802a924c5356cf5afc8ab7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b6d8eb9 R-maint-sig mass rebuild