$ git clone -n https://src.fedoraproject.org/rpms/ghc-hostname.git /var/lib/mock/f38-build-side-42-init-devel-719511-27296/root/chroot_tmpdir/scmroot/ghc-hostname
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-719511-27296/root/chroot_tmpdir/scmroot/ghc-hostname'...
$ git fetch origin 836100e6d38f85016e02d7fcf42ed68a7a2d5304:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-hostname
 * [new ref]         836100e6d38f85016e02d7fcf42ed68a7a2d5304 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 836100e Convert to %autorelease and %autochangelog