If one attempts to set a breakpoint in one line function:
e.g for this code:

def f(x): return x*x

z=23

pdb silently sets a breakpoint on the line right after
the function definition (i.e. outside the function body!):

../python pdb.py.v1.66 pdb_one_line_func 
> <string>(1)?()
(Pdb) b f
Breakpoint 1   /src/Lib/pdb_one_line_func:3
(Pdb) c
> /src/Lib/pdb_one_line_func(3)?()
-> z=23

It's probably acceptable to limit pdb breakpoints to
multiline functions, but i don't think, it's acceptable
to create wrong breakpoints.

Note: that anyone attempting to fix this should also
take a look at bug 875404 (global statment causes
breakpoints..), as both bugs are caused by
pdb.checkline() logic

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Patch 1003640 should fix this problem

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Fixed by checking in patch 1003640.