$ git clone -n https://src.fedoraproject.org/rpms/icecat.git /var/lib/mock/f38-build-side-42-init-devel-872898-28445/root/chroot_tmpdir/scmroot/icecat
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-872898-28445/root/chroot_tmpdir/scmroot/icecat'...
$ git fetch origin c51f3a7673dd43fd82f5d6f0765cd29ede0b214b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/icecat
 * [new ref]         c51f3a7673dd43fd82f5d6f0765cd29ede0b214b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c51f3a7 Downgrade optimization level in i686