bug#5794: 23.1; UnicodeEncodeError in python-shell

[Chong Yidong]

>>> When python shell invoked via C-c C-c, its stdout encoding is set to
>>> None and unicode characters can not be printed.
>
>> This is due to the following line in `run-python'
>>   (process-connection-type nil))
>> I'm not sure why using a pipe rather than a pty makes a difference,
>> though.
>
> This is probably for python builtin help() function, which can use
> pager to scroll documentation page by page. When help() detects that
> terminal is a pipe, it disables interactive scrolling and just prints
> full output as is.

I've changed python.el in the trunk to use a pty; this should remove the
problem.