False positive no-member after assert isinstance

[fluffy-critter]

Steps to reproduce

In https://github.com/PlaidWeb/Authl/blob/dc53e065e7cfe5e21bcfb169aea4588293531da8/tests/handlers/test_fediverse.py#L89:

    result = handler.check_callback(result.url, parse_args(result.url), {})
    assert isinstance(result, disposition.Verified)
    assert result.identity == 'https://mastodon.example/@moo'
    assert result.redir == 'qwerpoiu'
    assert result.profile == { 
        'name': 'moo friend',
        'bio': 'a cow',
        'avatar': 'https://placekitten.com/1280/1024',
        'homepage': 'https://moo.example',
        'pronouns': 'moo/moo'
    }

Current behavior

tests/handlers/test_fediverse.py:93:11: E1101: Instance of 'Error' has no 'profile' member (no-member)

Expected behavior

In this particular test, result can never be disposition.Error and there's even a previous assertion to ensure that it's disposition.Verified which does have the 'profile' member. I assume that there's some erroneous caching of result's type from another test.

pylint --version output

Result of pylint --version output:

pylint 3.0.0-a4
astroid 2.6.2
Python 3.8.6 (default, Jan  6 2021, 12:14:27) 
[Clang 12.0.0 (clang-1200.0.32.28)]

[jolaf]

I've encountered this error too – twice already.