[issue16373] Recursion error comparing set() and MutableMapping.keys()

[Serhiy Storchaka]

Serhiy Storchaka added the comment:

The core of the problem is in Set.

import collections.abc
class S(collections.abc.Set):
    def __contains__(self, key): return False
    def __iter__(self): return iter(())
    def __len__(self): return 0

S() < set() is False.
set() < S() fails.

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue16373>
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