Yarn: Licence generateDisclaimer - Outputs "junk" to stdout

Do you want to request a _feature_ or report a _bug_?
Bug

What is the current behavior?
When running yarn licenses generateDisclaimer and piping stdout to a file, I would expect to get only the disclaimer text to easily integrate this feature with CI etc. Instead, the first few lines look like this:

yarn licenses v0.15.1
info "[email protected]" is an optional dependency and failed compatibility check. Excluding it from installation.
THE FOLLOWING SETS FORTH ATTRIBUTION NOTICES FOR THIRD PARTY SOFTWARE THAT MAY BE CONTAINED IN PORTIONS OF THE XXX PRODUCT.

The third line is correct, but the two proceeding have nothing to do with the disclaimer.

At the end of the document, there is a line that says

Done in 5.45s.

This is also not a part of the disclaimer and should not be a part of the output.

I see four possible solutions.

• The first is to send all metadata about yarn to stderr
• The second is to specially handle generateDisclaimer
• The third is to create a global -q, --quiet flag
• The last is to add a -o --output option to generateDisclaimer that writes a file

If the current behavior is a bug, please provide the steps to reproduce.

1. Create a package.json with some dependencies (preferably with some incompatible peerDependencies)
2. Run yarn licenses generateDisclaimer > DISCLAIMERS.txt
3. Open DISCLAIMERS.txt
4. Look at the beginning and end of the document

What is the expected behavior?
The disclaimer file is generated without the parts preceding THE FOLLOWING SETS FORTH ATTRIBUTION, and without Done in 5.45s. at the end.

Please mention your node.js, yarn and operating system version.

$ yarn --version
0.15.1
$ node --version
v6.4.0
$ uname -a
Linux thor.osl.manamind.com 4.7.7-200.fc24.x86_64 #1 SMP Sat Oct 8 00:21:59 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux