$ git clone -n https://src.fedoraproject.org/rpms/ghc8.10.git /var/lib/mock/f38-build-side-42-init-devel-918018-28734/root/chroot_tmpdir/scmroot/ghc8.10
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-918018-28734/root/chroot_tmpdir/scmroot/ghc8.10'...
$ git fetch origin 511cf979f74f38a756e38f6d932bb64acda553ae:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc8.10
 * [new ref]         511cf979f74f38a756e38f6d932bb64acda553ae -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 511cf97 %ghc_devel_prof was dropped in ghc-srpm-macros-1.6.0