Quickstart: should run quickstart failed

[flaky-bot]

Note: #337 was also for this test, but it was closed more than 10 days ago. So, I didn't mark it flaky.

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commit: 61c49e2
buildURL: Build Status, Sponge
status: failed

Test output

expected 'Command failed: node ./quickstart.js …' to match /ALREADY_EXISTS/
AssertionError: expected 'Command failed: node ./quickstart.js …' to match /ALREADY_EXISTS/
    at Context. (test/quickstart.js:37:14)
    at processImmediate (internal/timers.js:461:21)