Use global print output

[schneems]

Switches from stdout to the global writer which defaults to stderr. This swich guarantees consistent print output when the print stream is dropped and then we have to construct a new one to emit an error message.

[colincasey]

Looks good but can you explain the rationale behind switching from stdout to stderr again? What's the benefit there?

[schneems]

Looks good but can you explain the rationale behind switching from stdout to stderr again? What's the benefit there?

Sure. Here's an internal link https://salesforce-internal.slack.com/archives/C02GZCPPV38/p1738340566002289.

For everyone else, as an oversimplification: Stdout is for machines, stderr is for humans. Here's some more info https://unix.stackexchange.com/questions/331611/do-progress-reports-logging-information-belong-on-stderr-or-stdout.

As a related sidebar: I'm wanting to propose that $ pack CLI re-routes all buildpack output to stderr so that we can allow using pack build with unix pipes by emitting only specific, structured information to stdout. There's also some ordering issues that are related:

• Non-deterministic ordering of buildpack stdout/stderr buildpacks/pack#2330 (so we should default to one or the other, and stderr is the more correct output)