$ git clone -n https://src.fedoraproject.org/rpms/ghc-js-chart.git /var/lib/mock/f40-build-742195-110610/root/chroot_tmpdir/scmroot/ghc-js-chart
Cloning into '/var/lib/mock/f40-build-742195-110610/root/chroot_tmpdir/scmroot/ghc-js-chart'...
$ git fetch origin 54590467859195dff4ea4b6169376eabce5812fa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-js-chart
 * [new ref]         54590467859195dff4ea4b6169376eabce5812fa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5459046 tweak datadir and bump release over criterion (#2185353)