Edit commit message on a merge proposal is broken

The test_set_commit_message Windmill test is failing, and I can confirm the same behaviour on launchpad.dev/.

Failure in test lp.code.windmill.tests.test_branch_merge_proposal.TestCommitMessage.test_set_commit_message
Traceback (most recent call last):
  File "/devel/launchpad/windmill-more-problems/lib/lp/testing/__init__.py", line 449, in run
    testMethod()
  File "/devel/launchpad/windmill-more-problems/lib/lp/code/windmill/tests/test_branch_merge_proposal.py", line 61, in test_set_commit_message
    client.asserts.assertText(
  File "/devel/launchpad/rocketfuel/eggs/windmill-1.3beta3_lp_r1440-py2.4.egg/windmill/authoring/__init__.py", line 161, in __call__
    return self.exec_method(self.action_name, **kwargs)
  File "/devel/launchpad/rocketfuel/eggs/windmill-1.3beta3_lp_r1440-py2.4.egg/windmill/authoring/__init__.py", line 214, in _exec_test
    raise WindmillTestClientException(result['result'])
WindmillTestClientException: {'suite_name': 'Commit message editing.', 'result': False, 'starttime': '2009-9-28T18:51:11.604Z', 'params': {'xpath': '//div[@id="edit-description"]//div[@class="yui-editable_text-text"]', 'validator': 'This is the commit message.'}, 'debug': "Text 'This is the commit message.' was not found in the provided node. Found instead: ", 'output': None, 'endtime': '2009-9-28T18:51:11.604Z', 'method': 'asserts.assertText'}

Oops-Id: OOPS-1397T652
Exception-Type: ValueError
Exception-Value: Unicode results must have a text content type.
Date: 2009-10-28T13:31:21.031768+00:00
Page-Id: EntryField:EntryFieldResource
Branch: windmill-more-problems
Revision: 9793
User: Eric the Viking, 2436244, Eric the Viking, Eric the Viking
URL: http://code.launchpad.dev:8085/api/beta/%7Eperson-name14/product-name4/branch12/+merge/1/commit_message
Duration: 0.218192100525
Informational: False

%22This is the commit message.%22=
CHANNEL_CREATION_TIME=1256736680.77
CONTENT_LENGTH=29
CONTENT_TYPE=application/x-www-form-urlencoded; charset%3DUTF-8
GATEWAY_INTERFACE=CGI/1.1
HTTP_ACCEPT=application/xhtml+xml
HTTP_ACCEPT_CHARSET=ISO-8859-1,utf-8;q%3D0.7,*;q%3D0.7
HTTP_ACCEPT_ENCODING=gzip,deflate
HTTP_ACCEPT_LANGUAGE=en-us,en;q%3D0.5
HTTP_CACHE_CONTROL=no-cache
HTTP_COOKIE=%3Chidden%3E
HTTP_HOST=code.launchpad.dev:8085
HTTP_PRAGMA=no-cache
HTTP_REFERER=http://code.launchpad.dev:8085//%7Eperson-name14/product-name4/branch12/+merge/1
HTTP_USER_AGENT=Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.3) Gecko/20091020 Ubuntu/9.10 (karmic) Firefox/3.5.3
HTTP_X_CONTENT_TYPE_OVERRIDE=application/json
HTTP_X_HTTP_METHOD_OVERRIDE=PATCH
HTTP_X_REQUESTED_WITH=XMLHttpRequest
PATH_INFO=/api/beta/%7Eperson-name14/product-name4/branch12/+merge/1/commit_message
QUERY_STRING=
REMOTE_ADDR=127.0.0.88
REQUEST_METHOD=POST
SCRIPT_NAME=
SERVER_NAME=lilium
SERVER_PORT=8085
SERVER_PROTOCOL=HTTP/1.1
SERVER_SOFTWARE=zope.server.http (HTTP)
launchpad_tests=%3Chidden%3E
wsgi.input=%3Chidden%3E
zc.zservertracelog.interfaces.ITraceLog=%3Chidden%3E

Traceback (most recent call last):
  Module zope.publisher.publish, line 136, in publish
    response.setResult(result)
  Module zope.publisher.http, line 783, in setResult
    r, headers = self._implicitResult(r)
  Module zope.publisher.browser, line 686, in _implicitResult
    body, headers = super(BrowserResponse, self)._implicitResult(body)
  Module zope.publisher.http, line 809, in _implicitResult
    raise ValueError(
ValueError: Unicode results must have a text content type.