[FIX] mail: preserve timezone offset when extracting the Date of received mails

Previously the date was treated as UTC, ignoring
the specified timezone offset. As a result the
displayed date was off by the actual UTC offset
of the sender's timezone

bzr revid: odo@openerp.com-20120702093523-fttsemnl1irc7917

addons/mail/mail_message.py

@@ -24,6 +24,7 @@ import base64
 import dateutil.parser
 import email
 import logging
+import pytz
 import re
 import time
 from email.header import decode_header
@@ -398,7 +399,15 @@ class mail_message(osv.osv):
 
         if 'Date' in fields:
             date_hdr = decode(msg_txt.get('Date'))
-            msg['date'] = dateutil.parser.parse(date_hdr).strftime("%Y-%m-%d %H:%M:%S")
+            parsed_date = dateutil.parser.parse(date_hdr)
+            if parsed_date.utcoffset() is None:
+                # naive datetime, so we arbitrarily decide to make it
+                # UTC, there's no better choice. Should not happen,
+                # as RFC2822 requires timezone offset in Date headers.
+                stored_date = parsed_date.replace(tzinfo=pytz.utc)
+            else:
+                stored_date = parsed_date.astimezone(pytz.utc)
+            msg['date'] = stored_date.strftime("%Y-%m-%d %H:%M:%S")
 
         if 'Content-Transfer-Encoding' in fields:
             msg['encoding'] = msg_txt.get('Content-Transfer-Encoding')