$ git clone -n https://src.fedoraproject.org/rpms/source-to-image.git /var/lib/mock/f40-build-2216225-52484/root/chroot_tmpdir/scmroot/source-to-image
Cloning into '/var/lib/mock/f40-build-2216225-52484/root/chroot_tmpdir/scmroot/source-to-image'...
$ git fetch origin f788cdb0b852bd2afb6bdcb383c4e9de82d1c1ad:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/source-to-image
 * [new ref]         f788cdb0b852bd2afb6bdcb383c4e9de82d1c1ad -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f788cdb Update to v1.3.9