$ git clone -n https://src.fedoraproject.org/rpms/icestorm.git /var/lib/mock/f40-build-2236959-53529/root/chroot_tmpdir/scmroot/icestorm
Cloning into '/var/lib/mock/f40-build-2236959-53529/root/chroot_tmpdir/scmroot/icestorm'...
$ git fetch origin b0a9c4dc55a19c0ae6170dc043bb354f6140e4f2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/icestorm
 * [new ref]         b0a9c4dc55a19c0ae6170dc043bb354f6140e4f2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b0a9c4d update snapshot