QNetworkReply causes segfault

问题

I'm trying to write some kind of API client for PyQt4-based app. And, following this documentation i wrote this code:

from PyQt4 import QtCore, QtNetwork


class API(QtCore.QObject):
    def processResponse(self, response):
        print 'response'
        response.deleteLater()

    def processError(self, error):
        print 'error'

    def authenticate(self, authUrl, login, password):
        manager = QtNetwork.QNetworkAccessManager()
        request = QtNetwork.QNetworkRequest(QtCore.QUrl(authUrl))
        reply = manager.get(request)
        reply.error.connect(self.processError)
        reply.finished.connect(self.processResponse)
        return reply

    def authenticate2(self, authUrl, login, password):
        manager = QtNetwork.QNetworkAccessManager()
        request = QtNetwork.QNetworkRequest(QtCore.QUrl(authUrl))
        self.reply = manager.get(request)
        self.reply.error.connect(self.processError)
        self.reply.finished.connect(self.processResponse)
        return self.reply


p = API()
z = p.authenticate('http://dev.dentv.ru/edda/v1/token/', 'test', 'test')
print z
print z.isFinished()

The first problem is -- none of signals (processResponse, processError) gets called (even if I declare the connection with self.connect(.., SIGNAL(..), ..)). The second problem is that this code causes a segfault on the last line, when i'm calling isFinished method. If I call this method inside the API method it works properly.

I was thinking, that the cause is that reply object get garbage-collected or somehow deleted, so i wrote the second version of authenticate method with explicit reply binding to object variable. It causes segfault too.

What's the problem with my code?