Remove puts output from `head`

[fletchto99]

Having output in the head can cause brew bundle to break. For example, I've got an application setup locally which loads formulas into to JSON via brew bundle. Since I had this formula tapped when loaded it would output via puts the TRAVIS_COMMIT env variable into the output making the json invalid causing the application setup via brew bundle to fail.

[mistydemeo]

For context, brew bundle itself parses the JSON output of brew info --installed --json=v1, which is where this would have caused that output not to parse. 😄 https://github.com/Homebrew/homebrew-bundle/blob/master/lib/bundle/locker.rb#L80

[iceman1001]

Nice find! It would however be nice to still get the output for the env variable instead of just removing it.

[fletchto99]

Any output here will break brew bundle. Is there a reason its needs to be output? Perhaps it could be output during the install instead?

[iceman1001]

Not informed in exact reason for printing / usage it there, I would guess it was handy. The output is good when debugging the travis integration. If we can print it during install, it would be fine. lets ask @merlokk if the output was used in any homebrew tests.

[mistydemeo]

Printing during install would be a lot safer than printing it at load-time! You could also guard the puts so it only prints if that variable is set. Printing to stderr would also be a bit safer, to avoid polluting the stream of something else that's consuming machine-readable output from stdout like what happened here.

[iceman1001]

Looking forward to see the PR become enhanced with @mistydemeo 's suggestion

[iceman1001]

Merlokk was fine with removing this output.

[iceman1001]

Thanks for this find and fix!