KeyError: 'captcha_redirect'

[anonymous]

How to Reproduce

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

(please provide additional details here)

Request parameters:

{'__FORM_TOKEN': u'8d5c9b7f1f177b0063e7504a',
 'recaptcha_challenge_field': u'03AHJ_VusVqqXe6Y3jp6zOjHKThxdHuyNSRCim601JPpYZQ9H3-FdHx7x7R6vvI_Anu1YtLLV716jNll37gPHQfjXAogUnGMMvaez2KVSZNCP-7a5jKHED_hU-9bPyAecJ129KrXGZSAkLcQ6BsDTovwxzNr7D7AXZeA',
 'recaptcha_response_field': u'genners  johnny'}

User agent: Mozilla/5.0 (Windows NT 5.1; rv:2.0.1) Gecko/20100101 Firefox/4.0.1

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'

[addyosmani]

Duplicate of #9582.