[FIX] generate_tracking_message_id: use more randomness to avoid duplicates

When several message IDs had to be generated for the same
record at the same time, there was a high chance to
get non-unique results. This possibly lead to data loss because
some mail implementations might ignore multiple mails with the
same ID (including OpenERP itself). On most operating systems
the available time resolution precision is better than what
we used (due to the float rounding of `%s`).
Adding a bit of randomness doesn't hurt, as OpenERP will
be used in increasingly distributed environments, so
we now add an extra random part as well.

bzr revid: odo@openerp.com-20121022162421-qr7nq8idihp5781u

openerp/tools/misc.py

@@ -27,12 +27,11 @@ Miscellaneous tools used by OpenERP.
 """
 
 from functools import wraps
-import inspect
 import subprocess
 import logging
 import os
+import random
 import re
-import smtplib
 import socket
 import sys
 import threading
@@ -40,13 +39,6 @@ import time
 import zipfile
 from collections import defaultdict
 from datetime import datetime
-from email.MIMEText import MIMEText
-from email.MIMEBase import MIMEBase
-from email.MIMEMultipart import MIMEMultipart
-from email.Header import Header
-from email.Utils import formatdate, COMMASPACE
-from email import Utils
-from email import Encoders
 from itertools import islice, izip
 from lxml import etree
 from which import which
@@ -363,7 +355,12 @@ def generate_tracking_message_id(res_id):
        Used to track the replies related to a given object thanks to the "In-Reply-To"
        or "References" fields that Mail User Agents will set.
     """
-    return "<%s-openerp-%s@%s>" % (time.time(), res_id, socket.gethostname())
+    try:
+        rnd = random.SystemRandom().random()
+    except NotImplementedError:
+        rnd = random.random()
+    rndstr = ("%.15f" % rnd)[2:] 
+    return "<%.15f.%s-openerp-%s@%s>" % (time.time(), rndstr, res_id, socket.gethostname())
 
 def email_send(email_from, email_to, subject, body, email_cc=None, email_bcc=None, reply_to=False,
                attachments=None, message_id=None, references=None, openobject_id=False, debug=False, subtype='plain', headers=None,