os.walk bug?

[Tim Peters]

[Gabriel Cosentino de Barros]
...
> for root, dirs, files in os.walk('t:\'): 
>         # -- do stuff 
>         print "working on", root                
>         # -- stuff done 
> 
>         print 'DEBUG: dirs =', dirs 
>         for d in dirs: 
>                 # -- remove archive 
>                 if d[:2] == '20': 
>                         print "--- removing:", d 
>                         dirs.remove(d) 

You're mutating a list while iterating over it.  This has odd effects.
 They're defined in the Language Reference Manual, but it's best to
avoid them.  Change

for d in dirs:

to

for d in dirs[:]:

and you should stop getting surprised.  That avoids surprise by
iterating over a copy of the list.  Then it doesn't matter that you
mutate the original list inside the loop.