Make __eq__ and __hash__ of AbelianGroup_class consistent

[jdemeyer]

AbelianGroup_class inherits its __hash__ from UniqueRepresentation but it has a different __eq__:

__eq__ = is_isomorphic

Either we should remove that special __eq__ or we should make __hash__ consistent with __eq__.

[jhpalmieri]

Well, I removed __eq__ and __ne__ and there were only a few doctest failures. So I say we go this route.

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New commits:

​6c25916

trac 25935: remove __eq__ for AbelianGroup_class: it should inherit __eq__

[jhpalmieri]

I'll mark this as "needs review", but feel free to disagree with the approach.

[jdemeyer]

I agree with the proposal, but we'll need to see if it passes tests.

[jhpalmieri]

Note that I did not add __hash__ = UniqueRepresentation.__hash__. That can wait until a Python 3 focused ticket, like #24551.

[jdemeyer]

Replying to jhpalmieri:

Note that I did not add __hash__ = UniqueRepresentation.__hash__.

There shouldn't be a reason for that.