Empty header causes PHP built-in web server to hang

 [2014-03-05 22:38 UTC] jon dot dufresne at gmail dot com

Description:
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Serving the test script below through the PHP built-in web server causes the server to hang. A response is never generated. This script works through mod_php. Once the server hangs, Ctrl-C is insufficient to quit. I am only able to quit using the kill command.

Test script:
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<?php

header(' ', false, 200);

Expected result:
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The web server should serve a response with a 200 status code.

Actual result:
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Web server hangs. Requires killing with the kill command.

 [2014-07-06 02:25 UTC] yohgaki@php.net

It hangs with 5.5 branch at least.
I guess built in server is trying to read inputs.