Without this, you can't close the standard input stream without also closing the standard output stream. One can try to redirect
standard output to error, but having a reference on the error stream keeps a reference on the stdio stream, so closing stdio
won't decrement the reference count enough to actually close the stream.
This makes it possible to use programs over SSH that take their input over standard input without any temporary files/redirection, and get the output back over standard output.
Without this, you can't close the standard input stream without also closing the standard output stream. One can try to redirect standard output to error, but having a reference on the error stream keeps a reference on the stdio stream, so closing stdio won't decrement the reference count enough to actually close the stream.
This makes it possible to use programs over SSH that take their input over standard input without any temporary files/redirection, and get the output back over standard output.