TypeError: unsupported operand type(s) for -: 'datetime.datetime' and 'NoneType'

[admin]

How to Reproduce

While doing a GET operation on /agilo-backlog, Trac issued an internal error.

(please provide additional details here)

Request parameters:

{'name': u'Sprint Backlog', 'scope': u'Websad Sprint 1'}

User Agent was: Mozilla/5.0 (Windows; U; Windows NT 5.2; pt-BR; rv:1.9.0.11) Gecko/2009060215 Firefox/3.0.11 (.NET CLR 3.5.30729)

System Information

Trac	0.11.4
Python	2.5.4 (r254:67916, Dec 23 2008, 15:10:54) [MSC v.1310 32 bit (Intel)]
setuptools	0.6c9
SQLite	3.3.4
pysqlite	2.3.2
Genshi	0.5.1
Agilo	unknown
Subversion	1.5.6 (r36142)
jQuery:	1.2.6

Python Traceback

Traceback (most recent call last):
  File "C:\Documents and Settings\taz.TAZWIN\Desktop\Agilo_installer\trac_svn\lib\site-packages\trac-0.11.4-py2.5.egg\trac\web\main.py", line 435, in _dispatch_request
  File "C:\Documents and Settings\taz.TAZWIN\Desktop\Agilo_installer\trac_svn\lib\site-packages\trac-0.11.4-py2.5.egg\trac\web\main.py", line 205, in dispatch
  File "C:\Program Files\Agilo\lib\site-packages\binary_agilo-pro_1.0_beta-py2.5.egg\agilo\scrum\backlog\web_ui.py", line 258, in process_request
    self.is_allowed_to(req, backlog, BacklogAction.EDIT) and \
  File "C:\Program Files\Agilo\lib\site-packages\binary_agilo-pro_1.0_beta-py2.5.egg\agilo\scrum\backlog\web_ui.py", line 777, in is_allowed_to
    return action in self.get_allowed_actions(req, backlog)
  File "C:\Program Files\Agilo\lib\site-packages\binary_agilo-pro_1.0_beta-py2.5.egg\agilo\scrum\backlog\web_ui.py", line 741, in get_allowed_actions
    sprint_buttons = self._add_sprint_backlog_buttons(sprint, backlog, permission_cache)
  File "C:\Program Files\Agilo\lib\site-packages\binary_agilo-pro_1.0_beta-py2.5.egg\agilo\scrum\backlog\web_ui.py", line 690, in _add_sprint_backlog_buttons
    sprint_started_at_max_one_day_ago = (to_datetime(None) - sprint.start) < timedelta(days=1)
TypeError: unsupported operand type(s) for -: 'datetime.datetime' and 'NoneType'

[rblank]

PluginIssue (AgiloForScrum). Please report it to the plugin maintainer.