As a user, I expect to be able to compare the different parts a `dict`
in the same manner.

Currently, `PyDictValues` does not implement the `dictview_richcompare`, causing the `__eq__` to always return false, even if the values are identical.


```
my_dict = {'foo': 'bar'}
dict_copy = my_dict.copy()
other_dict = {'foo': 'bar', 'bar': 1234}

assert my_dict.keys() == my_dict.keys()
assert my_dict.keys() == dict_copy.keys()
assert my_dict.keys() != other_dict.keys()

assert my_dict.items() == my_dict.items()
assert my_dict.items() == dict_copy.items()
assert my_dict.items() != other_dict.items()

assert my_dict.values() == my_dict.values()
assert my_dict.values() == dict_copy.values()
assert my_dict.values() != other_dict.values()

```

See also issue12445 which was a similar proposal rejected in the past.

Based on the current status of the discussion in python-dev, the most agreed upon solution so far seems to be updating the documentation to mention this behavior, rather than modifying the existing behavior. I opened a PR which updates the documentation for dict.values() to mention this, feel free to leave any suggestions.

python-dev discussion archive: https://mail.python.org/archives/list/python-dev@python.org/thread/R2MPDTTMJXAF54SICFSAWPPCCEWAJ7WF/#723CHZBH4ZBKQJOOPXFFX3HYSPDBPDPR

Added Brett to the nosy list since he was the one who suggested a documentation change.

Reopening the issue for adding the documentation clarification, that comparing the values view of two dictionaries will always return false (as was suggested in the ML discussion https://mail.python.org/archives/list/python-dev@python.org/message/K3SYX4DER3WAOWGQ4SPKCKXSXLXTIVAQ/). A month ago, I opened to PR to add the clarification to the documentation for dict.values(): https://github.com/python/cpython/pull/14954/files.

It probably went unnoticed because the issue had already been closed (which I hadn't realized at the time).

New changeset 6472ece5a0fe82809d3aa0ffb281796fcd252d76 by Brett Cannon (Kyle Stanley) in branch 'master':
bpo-37585: Add clarification regarding comparing dict.values() (GH-14954)
https://github.com/python/cpython/commit/6472ece5a0fe82809d3aa0ffb281796fcd252d76

New changeset 3cd147bf599f116593dc06ed7dfe948b759aabd3 by Miss Islington (bot) in branch '3.7':
bpo-37585: Add clarification regarding comparing dict.values() (GH-14954)
https://github.com/python/cpython/commit/3cd147bf599f116593dc06ed7dfe948b759aabd3

New changeset 690a16d455603500a0c6df0bd87e49c9b37a6950 by Miss Islington (bot) in branch '3.8':
bpo-37585: Add clarification regarding comparing dict.values() (GH-14954)
https://github.com/python/cpython/commit/690a16d455603500a0c6df0bd87e49c9b37a6950