$ git clone -n https://src.fedoraproject.org/rpms/ghc-extensible-exceptions.git /var/lib/mock/f38-build-side-42-init-devel-771075-27757/root/chroot_tmpdir/scmroot/ghc-extensible-exceptions
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-771075-27757/root/chroot_tmpdir/scmroot/ghc-extensible-exceptions'...
$ git fetch origin ca3a4e97bd382c82f68427a877fe3897f9e11088:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-extensible-exceptions
 * [new ref]         ca3a4e97bd382c82f68427a877fe3897f9e11088 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ca3a4e9 bump %autorelease baserelease to upgrade from f37