sympy/sympy — pull request #7645 by certik (2014-06-26 21:09:54+00:00)
Title: Implement __ne__() by calling __eq__()

The __ne__() operator should return "not __eq__()". Alternatively, one can copy
& paste the algorithm from __eq__() and negate the answer right before each
return. But anything else means there is a potential bug.