Pylint not working when language server is on

[luabud]

Environment data

• VS Code version: 1.38.0
• Extension version (available under the Extensions sidebar): 2019.9.34911
• OS and version: Windows 10
• Python version (& distribution if applicable, e.g. Anaconda): 3.7.3
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): venv
• Relevant/affected Python packages and their versions: pylint 2.3.1,
• Jedi or Language Server? (i.e. what is "python.jediEnabled" set to; more info How to update the language server to the latest stable version #3977): Language Server

Expected behaviour

Having linting, pylint and LS enabled in user settings should provide linting messages from both pylint and the LS.

Actual behaviour

Only LS is displaying linting messages. In order to get pylint to work, the workaround is to explicitly enable it in the workspace settings.

Steps to reproduce:

Enable pylint in the user settings, and make sure linting and the LS are enabled.
Write a piece of code wrongly and notice that only the LS will display linting messages. We'd expect pylint to work as well.

cc @Anapo14

[DonJayamanne]

We'll need to triage this. If this is indeed a bug, then it's a regression and will need to be labeled accordingly.
Note, we'll need to identify the cause when triaging.

[kimadeline]

If python.linting.pylintEnabled is not explicitly set (so we rely on the default value), the code will consider it disabled, see that comment in src/client/linters/linterInfo.ts:

// If we're using new LS, then by default Pylint is disabled (unless the user provides a value).

Why do we have this behaviour?

Double-checked, stepping through the code without having python.linting.pylintEnabled set anywhere (so it should default to true) returns false: