$ git clone -n https://src.fedoraproject.org/rpms/tcpdump.git /var/lib/mock/f42-build-867492-175514/root/chroot_tmpdir/scmroot/tcpdump
Cloning into '/var/lib/mock/f42-build-867492-175514/root/chroot_tmpdir/scmroot/tcpdump'...
$ git fetch origin 98d035c5ab5b2424b7a03912031c5d31debc248b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/tcpdump
 * [new ref]         98d035c5ab5b2424b7a03912031c5d31debc248b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 98d035c Rebuilt for the bin-sbin merge (2nd attempt)