Not on the top of my head. The isinstance check is False as expected everywhere else, correct ?

I also see this in Python 2.7.5 with numpy built from a more or less recent master, using 32 bit MinGW. It is only the isinstance check that fails.

test_collections_hashable also fails here on python 3.4.3 and 3.5.0b4, win-amd64:

Python's test for "hashability" is at https://hg.python.org/cpython/file/c7273b46980c/Lib/_collections_abc.py#l73.

np.ndarray.__dict__["__hash__"] is <slot wrapper '__hash__' of 'numpy.ndarray' objects>, not None, hence isinstance(x, collections.Hashable) returns True.

hash(np.array([])) correctly raises TypeError.

Relevant Python docs:

• https://docs.python.org/3/reference/datamodel.html#object.__hash__
• https://docs.python.org/3/c-api/object.html#c.PyObject_HashNotImplemented

Marking this as something to take another look at for the 1.10 release.

What has happened with this? Anyone. We don't see errors on AppVeyor.

Closing, it seems the actual issue is lost in the haze of time. If needed please open a new issue with a reproducer.