$ git clone -n https://src.fedoraproject.org/rpms/python-eth-stdlib.git /var/lib/mock/f42-build-side-1-3502882-45979/root/chroot_tmpdir/scmroot/python-eth-stdlib
Cloning into '/var/lib/mock/f42-build-side-1-3502882-45979/root/chroot_tmpdir/scmroot/python-eth-stdlib'...
$ git fetch origin e3be8c1edb8f81cb61fbdb44bd1aa2f5dddeec92:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/python-eth-stdlib
 * [new ref]         e3be8c1edb8f81cb61fbdb44bd1aa2f5dddeec92 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e3be8c1 Fix FTBFS