Email with blank subject will fail

[xurizaemon]

If an email with a blank subject is submitted, the following error occurs (from my syslog):

Feb 15 03:05:22 mohua email2trac: Traceback (most recent call last):
Feb 15 03:05:22 mohua email2trac:   File "/usr/bin/email2trac", line 1642, in <module>#012    tktparser.parse(sys.stdin)
Feb 15 03:05:22 mohua email2trac:   File "/usr/bin/email2trac", line 961, in parse#012    m.replace_header('Subject', m['Subject'].replace('\r', '').replace('\n', ''))
Feb 15 03:05:22 mohua email2trac: AttributeError: 'NoneType' object has no attribute 'replace'

I can't find the subject requirement documented, except obliquely (?) in response to #124.

If a site expected error output without a subject (eg some_cmd.sh | mail trac@example.org) to be handled by email2trac, this could be a nasty gotcha for them when those errors weren't turned into incoming tickets.

Testing for subject and inserting a default one would be a more graceful solution than the current exit.

Using Email2Trac $Id: email2trac.py.in 305 2010-01-11 15:09:54Z bas $

[bas]

(In [316]) Fixed a bug when there is no subject line, closes #179