Clean bogus in-reply-to headers before store it

[gpoo]

There are some email clients that add noise to the header field in-reply-to. For example,
http://lists.openstack.org/pipermail/openstack-dev/2012-August.txt.gz :

From julien at danjou.info  Wed Aug  8 19:52:08 2012
From: julien at danjou.info (Julien Danjou)
Date: Wed, 08 Aug 2012 21:52:08 +0200
Subject: [openstack-dev] [ceilometer] weekly meeting - CloudWatch
        functionality
In-Reply-To: <[email protected]> (Nick Barcet's message of "Wed, 
 08 Aug 2012 17:45:54 +0100")
References: <[email protected]>
 <[email protected]>
Message-ID: <[email protected]>

On Wed, Aug 08 2012, Nick Barcet wrote:
[...]

The actual Message-id is <[email protected]>, without the garbage at the end (which is how it is in References).

[gpoo]

BTW, the consequence of having a bogus In-Reply-To data is that you cannot reconstruct a discussion thread, unless you want to deal with this bogus format.

Something that MLStats does not handle is multiple Message-ID in that header, which is a possibility according to the RFC 2822.

[gpoo]

Another example, the Message-ID in the 'In-Reply-To` field appears in a different order:

From yamamoto at valinux.co.jp  Sun Jun  1 03:18:49 2014
From: yamamoto at valinux.co.jp (YAMAMOTO Takashi)
Date: Sun,  1 Jun 2014 12:18:49 +0900 (JST)
Subject: [openstack-dev] [Neutron][L3] BGP Dynamic Routing Proposal
In-Reply-To: Your message of "Fri, 30 May 2014 16:50:09 -0700"
 <CABJepwg3DJT8ST0tS0Mi5P98ovgbjVB_n3DSvGniMYHEpqUkCw@mail.gmail.com>
References: <CABJepwg3DJT8ST0tS0Mi5P98ovgbjVB_n3DSvGniMYHEpqUkCw@mail.gmail.com>
Message-ID: <[email protected]>

[gpoo]

Something like this should work:

diff --git a/pymlstats/analyzer.py b/pymlstats/analyzer.py
index 8c0fa63..7f98bdd 100644
--- a/pymlstats/analyzer.py
+++ b/pymlstats/analyzer.py
@@ -87,8 +87,7 @@ class MailArchiveAnalyzer:
                         'in-reply-to',
                         'subject',
                         'body']
-    common_headers = ['message-id', 'in-reply-to', 'list-id',
-                      'content-type', 'references']
+    common_headers = ['message-id', 'list-id', 'content-type', 'references']

     def __init__(self, archive=None):
         self.archive = archive
@@ -155,6 +154,9 @@ class MailArchiveAnalyzer:
             filtered_message['date'] = msgdate
             filtered_message['date_tz'] = str(tz_secs)

+            in_reply_to = message.get('in-reply-to')
+            filtered_message['in-reply-to'] = re.sub(r'^.*[^<]*(<.*>).*', r'\1', in_reply_to)
+
             # Retrieve other headers requested
             for header in self.common_headers:
                 msg = message.get(header)