// AAA to stdout and BBB to stderr simultaneously produces
		// AAABBB or BBBAAA on the pipe, not something like AABBBA.
		// However, the exception to this is when the pipe fills: in that
		// case, Go's use of non-blocking I/O means that writing AAA
		// or BBB might be split across multiple system calls, making it
		// entirely possible to get output like AABBBA. The same problem