That is discussed extensively in the issues related to the OP. The problem is that package maintainers of distros actually check whether the GPG signature has changed in order to repackaged python projects for their distros.
$ curl -s $(curl -s https://pypi.org/pypi/cryptography/json | jq '.releases["2.2.2"][] | select(.has_sig) | .url' | sed -e 's/^"//' -e 's/"$//').asc
-----BEGIN PGP SIGNATURE-----
iQEzBAABCAAdFiEEBf2foWz3VzUNkaVgI1rl8Sn57ZgFAlq6dNgACgkQI1rl8Sn5
7Zg0Ygf/WzulfXom9qdbCHrUJh2xkTxPqK2/SUqDqOQ1OdKJm+MxDBcMhwrCdBDh
8+eXyPTLnnhPUcCSqVFcJeUu9KyKB2MhKi7gdBUHrDxjbufexxPC+L/KwjOq3nod
gL4OPHGGeX2ZgSlwFPR4zPIIheUmf9kPX88qtW8DD8zmuyhci6ibac9a/3fHkDVt
H27B+aqs+WObMjcfwZV7gMnRbZwUOBZvVFRxwfMHVuMpfbwhQC8HdBK74XKNaoTd
Golmpa5fqRm1sNquBz9YRVElWuw1qj1CZJhRBuR7V5xyPLX8J7EVUrYa70/fVtfr
hW7oAlNbMFYb58hGC9K20v6WX8XT2w==
=zox2
-----END PGP SIGNATURE-----