$ git clone -n https://src.fedoraproject.org/rpms/ghc-gi-ostree.git /var/lib/mock/f40-build-799816-142604/root/chroot_tmpdir/scmroot/ghc-gi-ostree
Cloning into '/var/lib/mock/f40-build-799816-142604/root/chroot_tmpdir/scmroot/ghc-gi-ostree'...
$ git fetch origin 91697673c554fe1b4d2f2de0ca2d02715fa65206:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-gi-ostree
 * [new ref]         91697673c554fe1b4d2f2de0ca2d02715fa65206 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9169767 Add a temporary override to CFLAGS