gracefully handle quitting after stdout closes (#300)
gracefully handle quitting after stdout closes (#300)

to avoid issues with `| head -n1`

See https://github.com/nodejs/node-v0.x-archive/issues/3211

Fixes https://github.com/heroku/toolbelt/issues/164
heroku/heroku-cli,heroku/cli,heroku/cli,heroku/heroku-cli,heroku/cli,heroku/heroku-cli,heroku/cli,heroku/heroku-cli