[Distutils] Look for wonky serials on PyPI

[Donald Stufft]

Hey all,

Just a heads up that due to hitting query timeouts when attempting to lookup serials I changed the way serials work and are queried on PyPI. This should have no visible changes to end users but keep an eye out for serials that don't look correct, particularly via bandersnatch failures. The good news is the new stuff is significantly faster (125x speed up on my local machine with no lock contention-- but more like 1250x given that it was timing out at 30s under load on PyPI) so API calls like XMLRLC list_packages_with_serial should be much faster now. 

Anyways. Let me know if anyone notices any broken bandersnatches. 

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