$ git clone -n https://src.fedoraproject.org/rpms/yasm.git /var/lib/mock/f42-build-side-1-3588722-46949/root/chroot_tmpdir/scmroot/yasm
Cloning into '/var/lib/mock/f42-build-side-1-3588722-46949/root/chroot_tmpdir/scmroot/yasm'...
$ git fetch origin d106c56ecf92921e018675f1f15f954c079bd55e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/yasm
 * [new ref]         d106c56ecf92921e018675f1f15f954c079bd55e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d106c56 update to git 121ab15