Description:
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On my developement-system (FreeBSD 5.1), msg_receive doesn't block until a new message arrives, even if MSG_IPC_NOWAIT is not passed to flags. msg_receive will return immediately, returning false.

Reproduce code:
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while (true) {
   $rcv = msg_receive ($key, 0, $msg_type, 65536, $msginfo, true, 0);
   var_dump ($rcv));
}

Expected result:
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The script should block until msg_receive returns true