Some more comments:

- Documentation needs a "versionadded" entry.

- A fate of calendar.timegm() needs to be decided.  If the decision is to deprecate it, deprecation warning need to be added to calendar module and docs updated accordingly.   Given that as implemented, time.timegm() is not a drop-in replacement for calendar.timegm(), deprecation may not be appropriate, it which case the difference between the two functions should probably be explained in the docs.