Cloned from upstream: https://pagure.io/freeipa/issue/6774 and clone of bug 1434845

Affected clients/servers:
- all RHEL 6.x IPA clients which uses IPA CLI tool `ipa` against 7.4 server.

Functional impact:
- minor performance regression (session re-negotiation). Command itself is executed as expected. Except following error/"gibberish" is shown to user of the `ipa` tool:

"""
 ipa: ERROR: unable to parse cookie header 'ipa_session=MagBearerToken=MiIjMRJWMAl1%2bazkGlIRns2iysA7wxc%2bpSenQtZEMKXSsRAXEcnw2wHEyzOyh8RHgIm5K7YvX1k1tPotRM2ztegX4ODAmOe26%2fP4FLu68AupejDBNmNIENfasrNhUiPowugkkRXBOD%2b%2bsGFFMUZ%2bP7AYPHoW3bE3uN4ftRQwftE11EFTti4a9fVwB4SLKiuU&expiry=1489670819868611;Max-Age=1800;path=/ipa;httponly;secure;': unsupported operand type(s) for +: 'NoneType' and 'datetime.timedelta'
"""

It can negatively affect automation tools which uses the CLI. But mainly it will be UX and reputation issue.

FreeIPA 4.5.0(1) server sends Set-Cookie header with Max-Age string, that is set by SessionMaxAge directive in httpd configuration. This is part of the header which older clients cannot parse. Older clients understand the cookie with expiration expressed this way: Expires=time_when_cookie_expires. In this format: Expires=Mon, 05 Jun 2017 17:10:07 GMT;

This bug is a proposal to work around the issue and change server in a way that it won't send Max-Age string.