[BUG] When run script loglevel is ignored unless set to "silent"

[crystalfp]

Current Behavior:

Running any script by npm shows a log of the script execution even if it is not an error. For example:
npm run my-script --loglevel error

> my_server@0.19.2 my-script D:\Project
> npx copyfiles --flat client/*.png server/http

The only way to silence the log message is by setting --loglevel silent
The same problem appears with npm@7
The problem is that setting loglevel in .npmrc silences also valid messages from npm. I had to spent too much time to debug why npm@7 was not installing my application. Removing .npmrc revealed a version problem in my packages.

Expected Behavior:

If it is not an error, nothing should be added by npm, only the script messages should appear.

Steps To Reproduce:

1. Create a project
2. Edit package.json and change the start script to "node -e console.log(\"Hello\")"
3. Run npm start It show the log
4. Run npm start --loglevel error It show the log message
5. Run npm start --loglevel silent No log message and the script output appears.'

Environment:

• OS: Windows 10 64bits and Ubuntu latest
• Node: 14.15.1 and 15.5.1
• npm: 6.4.8 and 7.4.0

[darcyclarke]

npm v6 is no longer in active development; We will continue to push security releases to v6 at our team's discretion as-per our Support Policy.

If your bug is preproducible on v7, please re-file this issue using our new issue template.

If your issue was a feature request, please consider opening a new RRFC or RFC. If your issue was a question or other idea that was not CLI-specific, consider opening a discussion on our feedback repo