$ git clone -n https://src.fedoraproject.org/rpms/ghc-tagged.git /var/lib/mock/f40-build-1998361-44231/root/chroot_tmpdir/scmroot/ghc-tagged
Cloning into '/var/lib/mock/f40-build-1998361-44231/root/chroot_tmpdir/scmroot/ghc-tagged'...
$ git fetch origin 9a0cef2d5a0b2bb065108f8ca21449cad0e50911:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-tagged
 * [new ref]         9a0cef2d5a0b2bb065108f8ca21449cad0e50911 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9a0cef2 https://hackage.haskell.org/package/tagged-0.8.7/changelog