AttributeError: 'NoneType' object has no attribute 'split'

[aahz@…]

How to Reproduce

While doing a POST operation on /ticket/411, Trac issued an internal error.

(please provide additional details here)

Request parameters:

{'__FORM_TOKEN': u'ebf9ea65f8fe75c21dc66626',
 'action': u'reopen',
 'action_change_owner_reassign_owner': u'anonymous',
 'author': u'aahz@pythoncraft.com',
 'cnum': u'7',
 'comment': u"As a new Trac user, I also find this behavior suboptimal.  It's been five years, please revisit this design flaw -- it makes it very difficult to update a ticket summary so that others don't need to scroll through the entire comment history.",
 'field_component': u'ticket system',
 'field_keywords': u'',
 'field_milestone': u'0.8',
 'field_priority': u'high',
 'field_severity': u'normal',
 'field_summary': u'Edit ticket description?',
 'field_type': u'defect',
 'field_version': u'0.7',
 'id': u'411',
 'preview': u'Preview',
 'replyto': u'',
 'ts': u'2006-06-21 08:26:44+00:00'}

System Information

Trac	0.11.5stable-r8354
Python	2.5.2 (r252:60911, Oct 5 2008, 19:29:17) [GCC 4.3.2]
setuptools	0.6c9
psycopg2	2.0.8
Genshi	0.6dev-r999
Pygments	1.0
Subversion	1.5.1 (r32289)

Python Traceback

Traceback (most recent call last):
  File "/usr/local/virtualenv/lib/python2.5/site-packages/Trac-0.11.5stable_r8354-py2.5.egg/trac/web/main.py", line 444, in _dispatch_request
    dispatcher.dispatch(req)
  File "/usr/local/virtualenv/lib/python2.5/site-packages/Trac-0.11.5stable_r8354-py2.5.egg/trac/web/main.py", line 205, in dispatch
    resp = chosen_handler.process_request(req)
  File "/usr/local/virtualenv/lib/python2.5/site-packages/Trac-0.11.5stable_r8354-py2.5.egg/trac/ticket/web_ui.py", line 182, in process_request
    return self._process_ticket_request(req)
  File "/usr/local/virtualenv/lib/python2.5/site-packages/Trac-0.11.5stable_r8354-py2.5.egg/trac/ticket/web_ui.py", line 531, in _process_ticket_request
    get_reporter_id(req, 'author'), field_changes)
  File "/usr/local/virtualenv/lib/python2.5/site-packages/Trac-0.11.5stable_r8354-py2.5.egg/trac/ticket/web_ui.py", line 1260, in _insert_ticket_data
    self._render_property_changes(req, ticket, field_changes)
  File "/usr/local/virtualenv/lib/python2.5/site-packages/Trac-0.11.5stable_r8354-py2.5.egg/trac/ticket/web_ui.py", line 1310, in _render_property_changes
    resource_new)
  File "/usr/local/virtualenv/lib/python2.5/site-packages/Trac-0.11.5stable_r8354-py2.5.egg/trac/ticket/web_ui.py", line 1344, in _render_property_diff
    old_list, new_list = old.split(), new.split()
AttributeError: 'NoneType' object has no attribute 'split'