Multiple linter support failing

[DonJayamanne]

Here's the output from the logs:

2018-09-12T23:52:33.0234844Z     ✖ Multiple linters -- error: No diagnostic messages.
2018-09-12T23:52:33.0235203Z 
2018-09-12T23:52:33.0236658Z ##[error]out\test\linters\lint.test.js(,): error : FAILED Linting - General Tests :: Multiple linters
2018-09-12T23:52:33.0237549Z ##[debug]Processed: ##vso[task.logissue type=error;sourcepath=D:\a\1\s\out\test\linters\lint.test.js;]FAILED Linting - General Tests :: Multiple linters
2018-09-12T23:52:33.0237762Z 

[d3r3kk]

I've skipped this test for now, as there needs to be some real work done to sort out the root cause.

The branch linting_test_failure in my personal repo here contains some console.log messages that show the behaviour symptomatic of the failure (you will likely have to run it on Windows, under Python3.7, and mutliple times before you see the failure occur).

Essentially the trouble is that the Promise on the executeCommand('python.runLinter') is resolving before the command is actually complete, and it also seems to be returning more than a single time, judging from the console output I've seen.

[brettcannon]

Attached is my log. If I have just flake8 on it's fine, and if I just have pep8 turned on it's, fine. But as soon as I have both on I get a message saying pep8 isn't installed and an error about TypeError: Converting circular structure to JSON (log).

[nullie]

https://github.com/Microsoft/vscode-python/blob/master/src/client/common/process/proc.ts#L172 method calls JSON.parse(JSON.stringify(options) (trying to make a deep copy?) , but fails on options.token._emitter._listeners