$ git clone -n https://src.fedoraproject.org/rpms/chez-scheme.git /var/lib/mock/f42-build-side-1-3497650-45961/root/chroot_tmpdir/scmroot/chez-scheme
Cloning into '/var/lib/mock/f42-build-side-1-3497650-45961/root/chroot_tmpdir/scmroot/chez-scheme'...
$ git fetch origin c370c4b4161c8d2fbecb4afb7df832480a4a6e10:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/chez-scheme
 * [new ref]         c370c4b4161c8d2fbecb4afb7df832480a4a6e10 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c370c4b 10.1 fixed the build on s390x (#2358214)