$ git clone -n https://src.fedoraproject.org/rpms/icestorm.git /var/lib/mock/f42-build-868815-176267/root/chroot_tmpdir/scmroot/icestorm
Cloning into '/var/lib/mock/f42-build-868815-176267/root/chroot_tmpdir/scmroot/icestorm'...
$ git fetch origin d62a2e1861facf05d0ded2265c58e849cab27e22:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/icestorm
 * [new ref]         d62a2e1861facf05d0ded2265c58e849cab27e22 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d62a2e1 update to newer snapshot