$ git clone -n https://src.fedoraproject.org/rpms/ghc-servant.git /var/lib/mock/f38-build-side-42-init-devel-1305178-30685/root/chroot_tmpdir/scmroot/ghc-servant
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-1305178-30685/root/chroot_tmpdir/scmroot/ghc-servant'...
$ git fetch origin b15631890da9c6994c7f5ab2aab01cae55d4ada0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-servant
 * [new ref]         b15631890da9c6994c7f5ab2aab01cae55d4ada0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b156318 Convert to %autorelease and %autochangelog