Revert our select changes since they are not needed.

This reverts changes from #1 and #2.

I believe our changes aren't necessary since `select.select` with a timeout of 0 results in a poll (same as using `select.poll`) and doesn't block (see https://docs.python.org/2/library/select.html#select.select).

`select.select` returns a list of FD's which are ready to be read from and we only read from `sys.stdin` if select returns a value which means read should never block since value is already available.