$ git clone -n https://src.fedoraproject.org/rpms/ghc-reflection.git /var/lib/mock/f39-build-1929769-43092/root/chroot_tmpdir/scmroot/ghc-reflection
Cloning into '/var/lib/mock/f39-build-1929769-43092/root/chroot_tmpdir/scmroot/ghc-reflection'...
$ git fetch origin 504a6c1439127500013652bd86ef3f7bfeed1fba:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-reflection
 * [new ref]         504a6c1439127500013652bd86ef3f7bfeed1fba -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 504a6c1 https://hackage.haskell.org/package/reflection-2.1.7/changelog