local-plugins relative paths are resolved relative to all paths not just the one the path directive is found

In GitLab by @graingert on Jul 13, 2020, 08:57

Please describe how you installed Flake8

pre-commit of course

Please provide the exact, unmodified output of flake8 --bug-report

{
  "dependencies": [],
  "platform": {
    "python_implementation": "CPython",
    "python_version": "3.8.2",
    "system": "Linux"
  },
  "plugins": [
    {
      "is_local": false,
      "plugin": "flake8-tidy-imports",
      "version": "4.1.0"
    },
    {
      "is_local": false,
      "plugin": "flake8_coding",
      "version": "1.3.2"
    },
    {
      "is_local": false,
      "plugin": "mccabe",
      "version": "0.6.1"
    },
    {
      "is_local": false,
      "plugin": "pycodestyle",
      "version": "2.6.0"
    },
    {
      "is_local": false,
      "plugin": "pyflakes",
      "version": "2.2.0"
    }
  ],
  "version": "3.8.3"
}

Please describe the problem or feature

the paths are resolved relative to all paths not just the one the path directive is found in eg:

.
└── foo
    ├── bar
    │   ├── baz
    │   └── .flake8
    ├── baz
    └── .flake8

[flake8:local-plugins]
...
paths = ./baz

when running flake8 --append-config=foo/bar/.flake8 --append-config=foo/.flake8 flake8 will add foo/baz and foo/bar/baz to LocalPlugins.paths

Start by reproducing the issue with the shown directory tree and the two --append-config arguments, then trace local-plugin paths configuration handling. Done means ./baz is resolved only relative to the configuration file containing the path directive, rather than being added relative to every loaded configuration path.