Fix pdb.line_prefix binding in print_stack_entry

Author: pareshjoshij

Lib/pdb.py

@@ -654,7 +654,7 @@ def _show_display(self):
 
     def _get_tb_and_exceptions(self, tb_or_exc):
         """
-        Given a tracecack or an exception, return a tuple of chained exceptions
+        Given a traceback or an exception, return a tuple of chained exceptions
         and current traceback to inspect.
 
         This will deal with selecting the right ``__cause__`` or ``__context__``
@@ -2429,7 +2429,9 @@ def print_stack_trace(self, count=None):
         except KeyboardInterrupt:
             pass
 
-    def print_stack_entry(self, frame_lineno, prompt_prefix=line_prefix):
+    def print_stack_entry(self, frame_lineno, prompt_prefix=None):     
+        if prompt_prefix is None:         
+            prompt_prefix = line_prefix
         frame, lineno = frame_lineno
         if frame is self.curframe:
             prefix = '> '