$ git clone -n https://github.com/xcp-ng-rpms/tcpdump.git /var/lib/mock/v8.3-incoming-9095-27939/root/chroot_tmpdir/scmroot/tcpdump
Cloning into '/var/lib/mock/v8.3-incoming-9095-27939/root/chroot_tmpdir/scmroot/tcpdump'...
$ git fetch origin 7077615107437398bf8fbe2cc817c31f69cfe818:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/tcpdump
 * [new ref]         7077615107437398bf8fbe2cc817c31f69cfe818 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7077615 Import tcpdump-4.9.2-5.xs8.src.rpm