Completely rewrote this patch to use subprocess.PIPE instead. The creation of the temporary file was overthinking the situation (it was attempting to avoid the small risk of deadlock when reading and writing stdin and stdout directly, however, since we're never doing those things at the same time, it's unnecessary).

This version of the patch also adds a test for the stdin functionality by calling 'tee' (which simply shunts stdin to stdout).

Add utility routine for passing stdin into subprocesses