$ ~/Projects/cpython/3.4/python -c '
class Foo(object):
    def __ne__(self, other):
        return "yup"
    def __eq__(self, other):
        return "nope"

class Bar(object):
    pass
        
print(object() != Foo(), object() == Foo())
print(Bar() != Foo(), Bar() == Foo())
'
yup nope
False nope
$

The output I would expect from this is

    yup nope
    yup nope

That is, even when the type of the left-hand argument is not a base class of the type of the right-hand argument, delegation to the right-hand argument is sensible if the left-hand argument does not implement the comparison.

Note that the output also demonstrates that this is already the behavior for `==`.  Only `!=` seems to suffer from this issue.