kdev-python warns you when the first argument of a class method is not called "self", because this is most likely a typo. For the __new__ method though, the common name of the argument is "cls", not "self"; so if the method name is __new__, kdev-python should check if the name is "cls", not if it is "self". See also this bug report: https://bugs.kde.org/show_bug.cgi?id=316899