CherryPy Unicode problem =>Ajax requests not possible with json

When performing a dojo XHR Request with Json as payload,
CherryPy receives a unicode/String “[object Object]” and no
(not even wrong encoded) other information about the data
inside the json object.

E.g.: JavaScript XHR Content:
…
handleAs: “json”,
content: {payload: {foo: bar}},
…

CherryPy receives: [object Object] <type ‘unicode’>

(from redmine: issue id 1011, created on 2012-05-15 by root, closed on 2013-01-07)