$ git clone -n https://src.fedoraproject.org/rpms/tcpdump.git /var/lib/mock/f41-build-852539-166391/root/chroot_tmpdir/scmroot/tcpdump
Cloning into '/var/lib/mock/f41-build-852539-166391/root/chroot_tmpdir/scmroot/tcpdump'...
$ git fetch origin b8d61ea98dcbca1953f332467543c8ee64223e05:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/tcpdump
 * [new ref]         b8d61ea98dcbca1953f332467543c8ee64223e05 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b8d61ea New version 4.99.5