$ git clone -n https://src.fedoraproject.org/rpms/ghc-extra.git /var/lib/mock/f40-build-1997902-44189/root/chroot_tmpdir/scmroot/ghc-extra
Cloning into '/var/lib/mock/f40-build-1997902-44189/root/chroot_tmpdir/scmroot/ghc-extra'...
$ git fetch origin e87011049e0d20237c346e27df00711558c419d2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-extra
 * [new ref]         e87011049e0d20237c346e27df00711558c419d2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e870110 https://hackage.haskell.org/package/extra-1.7.14/changelog