adress gaogao's comments about different ttys

Author: zelosleone

Lib/pdb.py

@@ -364,7 +364,7 @@ def __init__(self, completekey='tab', stdin=None, stdout=None, skip=None,
         bdb.Bdb.__init__(self, skip=skip, backend=backend if backend else get_default_backend())
         cmd.Cmd.__init__(self, completekey, stdin, stdout)
         sys.audit("pdb.Pdb")
-        if stdin and not getattr(stdin, 'isatty', lambda: False)():
+        if stdin is not None and stdin is not sys.stdin:
             self.use_rawinput = False
         self.prompt = '(Pdb) '
         self.aliases = {}