$ git clone -n https://src.fedoraproject.org/forks/hypersa/rpms/ghc-magic.git /var/lib/mock/f39-build-2226521-52943/root/chroot_tmpdir/scmroot/ghc-magic
Cloning into '/var/lib/mock/f39-build-2226521-52943/root/chroot_tmpdir/scmroot/ghc-magic'...
$ git fetch origin 313498b78caef077016e001d2453373022d62674:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/forks/hypersa/rpms/ghc-magic
 * [new ref]         313498b78caef077016e001d2453373022d62674 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 313498b rv64 rebuild