Parsing the HTTP "Date" header in Python

As per RFC 7231 §7.1.1.1: A recipient that parses a timestamp value in an HTTP header field MUST accept all three HTTP-date formats. These formats are then described as (with the first being the only preferred format; the latter 2 are designated as "obsolete"), converted for this post into strftime(3) syntax: %a, %d %b %Y %H:%M:%S %Z with the timezone always given as "GMT", but to be interpreted as …