In the following session, main.py is changed just before the restart
command. Pdb does not stop at Breakpoint 1 after the last continue.

$ python -m pdb main.py
> /path_to/main.py(1)<module>()
-> def foo():
(Pdb) import sys; print(sys.version)
3.2.2 (default, Dec 27 2011, 17:35:55) 
[GCC 4.3.2]
(Pdb) break foo
Breakpoint 1 at /path_to/main.py:1
(Pdb) list
  1 B-> def foo():
  2         x = 1
  3         x = 2
  4
  5     foo()
[EOF]
(Pdb) continue
> /path_to/main.py(2)foo()
-> x = 1
(Pdb) restart
Restarting main.py with arguments:
        main.py
> /path_to/main.py(1)<module>()
-> def bar():
(Pdb) list
  1 B-> def bar():
  2         x = 1
  3         x = 2
  4
  5     def foo():
  6         bar()
  7
  8     foo()
[EOF]
(Pdb) continue
The program finished and will be restarted
> /path_to/main.py(1)<module>()
-> def bar():
(Pdb)

Parsing the modules source seems a better way to fix this problem, see issue 14913.

See also how this is fixed at
http://code.google.com/p/pdb-clone/source/detail?r=6ad576592286a005694690906644cb3004090eeb

Worked for me on https://www.cheshiremouldings.co.uk/stair-parts/