python3 super doesn't work with PyQt classes

There is a simple program in python3:

from PyQt4 import QtCore
import PyQt4

class Bar(object):
    def __init__(self):
        print("Bar start")
        super(Bar, self).__init__()
        print("Bar end")

class FakeQObject(object):
    def __init__(self):
        print("FakeQObject start")
        super(FakeQObject, self).__init__()
        print("FakeQObject end")

class Foo(QtCore.QObject, Bar):
#class Foo(FakeQObject, Bar):
    def __init__(self):
        print("Foo start")
        super(Foo, self).__init__()
        print("Foo end")


print(Foo.__mro__)
print(PyQt4.QtCore.PYQT_VERSION_STR)
f = Foo()

a) When class Foo inherits from QtCore.QObject and Bar we get:

(<class '__main__.Foo'>, <class 'PyQt4.QtCore.QObject'>, <class 'sip.wrapper'>, <class 'sip.simplewrapper'>, <class '__main__.Bar'>, <class 'object'>)
4.9.4
Foo start
Foo end

b) When class Foo inherits from FakeQObject and Bar we get:

(<class '__main__.Foo'>, <class '__main__.FakeQObject'>, <class '__main__.Bar'>, <class 'object'>)
4.9.4
Foo start
FakeQObject start
Bar start
Bar end
FakeQObject end
Foo end

The question is: why in the a) case, Bar init is not called?

I found similar question here pyQt4 and inheritance but there are no good answers.

Thanks in advance!

---

Along with @nneonneo I also suspect that QtCore.QObject doesn't use the cooperative super.__init__ . If it did, you wouldn't have this problem.

However, you should be aware that at some point one of the base classes cannot use cooperative super because object won't have the method. Consider:

class Base():
    def __init__(self):
        print("initializing Base")
        super().__init__()
    def helper(self, text):
        print("Base helper")
        text = super().helper(text)
        text = text.title()
        print(text)

class EndOfTheLine():
    def __init__(self):
        print("initializing EOTL")
        super().__init__()
    def helper(self, text):
        print("EOTL helper")
        text = super().helper(text)
        return reversed(text)

class FurtherDown(Base, EndOfTheLine):
    def __init__(self):
        print("initializing FD")
        super().__init__()
    def helper(self, text):
        print(super().helper(text))

test = FurtherDown()
print(test.helper('test 1 2 3... test 1 2 3'))

and the output:

initializing FD
initializing Base
initializing EOTL
Base helper
EOTL helper
Traceback (most recent call last):
  File "test.py", line 28, in <module>
    print(test.helper('test 1 2 3... test 1 2 3'))
  File "test.py", line 25, in helper
    print(super().helper(text))
  File "test.py", line 7, in helper
    text = super().helper(text)
  File "test.py", line 17, in helper
    text = super().helper(text)
AttributeError: 'super' object has no attribute 'helper'

So, whichever class is going to be the End of the Line needs to not call super . Because there are other Qt methods you might want to override, that dictates that the Qt class must be the last one in the class header. By not having __init__ use cooperative super, even though it could, Qt is avoiding bugs further down when some other method is overridden.

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