bug#6099: 23.1; pdb can't invoke python directly

[Chong Yidong]

Dave Abrahams <dave@boostpro.com> writes:

> Let me try to fix the instructions for reproducing this, though:
>
> 1. `M-! echo 'print "hello"' > foo.py RET'
> 2. `M-S-: (pdb "python -m pdb foo.py") RET'
>
> Now hit return.  *gud-pdb* does _not_ contain ">>>"

I get a buffer containing

  Current directory is ~/
  > /home/cyd/foo.py(1)<module>()
  -> print "hello"
  (Pdb) 

With "(Pdb)" as the prompt.