Timezone abbreviations in dateutil

In Atoma, I use dateutil to parse dates found in RSS and Atom feeds. Some of these dates are RFC 822 which can include timezone abbreviations like EDT or PST.

Because these abbreviations are ambiguous dateutil does not parse them by default, so it throws an UnknownTimezoneWarning. However the few aliases used by RFC 822 are well defined and can be added manually:

tzinfos = {
    'UT': gettz('GMT'),
    'EST': -18000,
    'EDT': -14400,
    'CST': -21600,
    'CDT': -18000,
    'MST': -25200,
    'MDT': -21600,
    'PST': -28800,
    'PDT': -25200
}
dateutil.parser.parse(date_str, tzinfos=tzinfos)