Nightwatch 1.x: Not able to set output_folder in nightwatch settings.

No matter how I set to output_folder, the junit test reports is always generated in "test_output" folder.

Nightwatch settings:

{
    "output_folder": "reports",
    "src_folders": ["tests"],
    "page_objects_path": "./page-objects",
......

Nightwatch: 1.04, Node: v8.9.1, OS: windows 10 and linux, Selenium: selenium grid 3.11.0

[X] Please do not ask for assistance in the Issues list. Use the Mailing List or StackOverflow to ask questions or seek help.
[X] Use a meaningful title that would clearly and concisely explain the problem. For instance:
not helpful: "Issue with tags"
much better: "Tags don't work when combined with --skiptags option in some cases"
[X] Include a sample test (for complex scenarios) which would reproduce the problem you're experiencing. The test should be against a public url. The test and other info should be posted inline, attachments will not be accepted;
[ ] Include the verbose output, if possible (run nightwatch with --verbose argument);
[X] Also include: Nightwatch version, Node.js version, OS version and Selenium server version (including any driver version if applicable);
[X] Please try to avoid sending issues you have with Selenium (e.g. works perfectly in ChromeDriver but not in Safari)

nightwatchjs / nightwatch