How to Reproduce

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

''(please provide additional details here)''

Request parameters:

{'__FORM_TOKEN': u'2756692de139c891fcbfb965',
 'recaptcha_challenge_field': u'03AHJ_VuuJihrrDNCBnsUGszh8djsd7oqHqINvICXiiQ83QikJbheJx7zVkpVLsiywDNy-JQiRoQi68QAIR3rsZBt45YQGTsDxWrJoJdCOFqQSfyf7kq3RBWyzXPydOXjbbuEak83PpfWj_xUz9PEKMNL6Fdk62sOPYm-_d1frzudNIe4oRmBIzHs',
 'recaptcha_response_field': u'negulak testament'}

User agent: Mozilla/5#0 #compatible; MSIE 9#0; Windows NT 6#1; WOW64; Trident/5#0; SLCC2; #NET CLR 2#0#50727; #NET CLR 3#5#30729; #NET CLR 3#0#30729; Media Center PC 6#0; InfoPath#2; #NET4#0C; #NET4#0E#

System Information

''System information not available''

Enabled Plugins

''Plugin information not available''

Python Traceback

Traceback #most recent call last#:
  File "/usr/local/lib/python2#6/dist-packages/Trac-0#12#1-py2#6#egg/trac/web/main#py", line 511, in _dispatch_request
    dispatcher#dispatch#req#
  File "/usr/local/lib/python2#6/dist-packages/Trac-0#12#1-py2#6#egg/trac/web/main#py", line 202, in dispatch
    chosen_handler)
  File "/usr/local/lib/python2#6/dist-packages/Trac-0#12#1-py2#6#egg/trac/web/main#py", line 344, in _pre_process_request
    chosen_handler = filter_.pre_process_request#req, chosen_handler#
  File "/usr/local/lib/python2.6/dist-packages/TracSpamFilter-0.4.1dev_r10170-py2.6.egg/tracspamfilter/captcha/api.py", line 119, in pre_process_request
    del req.session['captcha_redirect']
KeyError: 'captcha_redirect'