Gracefully shut down server on "end" stdin

[jakehasler]

This is referencing issue #1753 - where react-scripts start wasn't closing upon stdin "end". I simply added one more condition on top of #2246 that would handle the "end" case and kill the process.

I am integrating CRA with an elixir-phoenix app and when using react-scripts start from within another process, it wasn't getting closed out when killing the main process. This made it difficult having to lsof -i $PORT and kill <pid> every time I had to restart the server.

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[gaearon]

Looks like this breaks our CI. Any ideas why?

[stale]

This pull request has been automatically marked as stale because it has not had any recent activity. It will be closed in 7 days if no further activity occurs.

[stale]

This pull request has been automatically closed because it has not had any recent activity. The conversation will be locked in 7 days unless the pull request is reopened. Thank you for your contribution.