$ git clone -n https://src.fedoraproject.org/forks/hypersa/rpms/ghc-js-chart /var/lib/mock/f39-build-2227251-53002/root/chroot_tmpdir/scmroot/ghc-js-chart
Cloning into '/var/lib/mock/f39-build-2227251-53002/root/chroot_tmpdir/scmroot/ghc-js-chart'...
$ git fetch origin f823bd23f0871aba05e0047472ac731b8fec379f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/forks/hypersa/rpms/ghc-js-chart
 * [new ref]         f823bd23f0871aba05e0047472ac731b8fec379f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f823bd2 rebuild