send errors and warnings to stderr

[jschauma]

This should help address #643, although possibly only in part.

[zliang-akamai]

Overall looks good to me!

[ezilber-akamai]

Looks good to me. Thank you for the contribution!

[lgarber-akamai]

Hey @jschauma, thanks for the contribution! Could you run make format on this PR to fix the lint CI failure?

[jschauma]

Sure - ran 'make format'. (I find ending the printf list of arguments with a comma a bit odd, but if that's what the formatter wants...?)

[lgarber-akamai]

Sure - ran 'make format'. (I find ending the printf list of arguments with a comma a bit odd, but if that's what the formatter wants...?)

Thank you! The formatter can make some odd decisions at times but we try to keep things as consistent as possible.

[lgarber-akamai]

FYI: I marked this PR as a breaking change since it technically could break scripts that check for error outputs in stdout. We'll mention this in the notes for the next release.

[zliang-akamai]

LGTM!

[atodorov]

@zliang-akamai I've been bitten by the behavior fixed by this PR - all of my VM provisioning fails b/c I get an extra

Using default values: {}; use the --no-defaults flag to disable defaults

in the json output. Strangely enough version 5.52.0 doesn't fail for me.

I will add a workaround on my side, however do yu mind pushing a new release to PyPI which includes this PR?