homepage

Thanks for noticing. The doc for ismethod() says:
 "Return true if the object is a bound method written in Python."
and the docstring agrees with that:
 "Return true if the object is an instance method. [...]"
So the change isn't properly a regression when reading the docs. On the other hand, it's true that some code may rely on the previous behaviour, and the discrepancy between getmembers() and a manual test can be confusing.
By the way, Python 3 has ismethod() right:
>>> class B:
... def f(self): pass
... 
>>> inspect.ismethod(B.f)
False
>>> inspect.ismethod(B().f)
True