super() raises “TypeError: must be type, not classobj” for new-style class

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The following use of super() raises a TypeError: why?

>>> from  HTMLParser import HTMLParser
>>> class TextParser(HTMLParser):
...     def __init__(self):
...         super(TextParser, self).__init__()
...         self.all_data = []
...         
>>> TextParser()
(...)
TypeError: must be type, not classobj

There is a similar question on StackOverflow: Python super() raises TypeError, where the error is explained by the fact that the user class is not a new-style class. However, the class above is a new-style class, as it inherits from object:

>>> isinstance(HTMLParser(), object)
True

What am I missing? How can I use super(), here?

Using HTMLParser.__init__(self) instead of super(TextParser, self).__init__() would work, but I would like to understand the TypeError.

PS: Joachim pointed out that being a new-style-class instance is not equivalent to being an object. I read the opposite many times, hence my confusion (example of new-style class instance test based on object instance test: https://stackoverflow.com/revisions/2655651/3).

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