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$ ~/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.