Output to file not working in >5.4.0

[sevaru]

Bug Report

• TSLint version: 5.4.2
• TypeScript version: 2.3.4
• Running TSLint via: CLI

TypeScript code being linted

tslint -p tsconfig.json -c tslint.json -o tslint-output.json

with tslint.json configuration:

{
    "rules": {
    	"no-var-keyword": true
    }
}

Actual behavior

With a versions start from 5.4.0 tslint-output.json file is empty. Works with 5.3.2, 5.3.0.

Expected behavior

tslint-output.json file has information about errors.

Note

I added only one rule in tslint.json just for sample purpose. It doesn't work with any other rule too.

[ajafff]

Seems like a race condition between asynchronously writing to file and the call to process.exit(code) after linting.
PR incoming.