Issue1785475

I have attached the patch file.
This patch will solve the following bugs

1768970 
-------
When you iterate over subclass of / sequence like
objects, only the pyget is called previously. 
Now it will call __getitem__ method by this patch 
so that we can extend sequence like objs and give 
our own impln to __getitem__.

https://sourceforge.net/tracker/?func=detail&atid=112867&aid=1768970&group_id=12867

1782565
-------
The output of repr() builtin func on string objects (str, unicode and subclasses of those) / __repr__()
of string objects doesnt match with that of CPython.

https://sourceforge.net/tracker/index.php?func=detail&aid=1782565&group_id=12867&atid=112867

1783868
-------
class weirdstr(str):
    def __getitem__(self, index):
        return weirdstr(2*str.__getitem__(self,index))

When you call __getitem__ of weirdstr obj, it calls
__getitem__ of str in turn, again from there(str) the 
call is made to __getitem__ of weirdstr, thus the call is made back and forth and finally throws 
StackOverflowError.

https://sourceforge.net/tracker/index.php?func=detail&aid=1783868&group_id=12867&atid=112867

Test case: Lib/test/test_builtin.py  

What's odd about the patch for #1768970 (use __getitem__ in the iter) is 
that we have to catch KeyErrors to work on Jython (without the catch 
iterating lists doesn't work correctly)

Whereas CPython actually allows KeyErrors to propagate through the 
iterator. I guess CPython is avoiding this by defining different 
iterators for builtins (e.g. list has its own listiterator type)

Python 2.5.1 (r251:54863, Aug 19 2007, 21:02:30) 
[GCC 4.0.1 (Apple Computer, Inc. build 5367)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> class Foo(object):
...     def __getitem__(self, i):
...             raise KeyError
... 
>>> iter(Foo()).next()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 3, in __getitem__
KeyError

with the patch:
Jython 2.3a0 on java1.5.0_13
Type "copyright", "credits" or "license" for more information.
>>> class Foo(object):
...     def __getitem__(self, i):
...             raise KeyError
... 
>>> iter(Foo()).next()
Traceback (innermost last):
  File "<console>", line 1, in ?
StopIteration:

most of the patch for #1782565 (broken repr on str/unicode subclasses) 
was incorporated in r4346

It's probably better to log separate issues for separate patch sets so 
it's easier to handle cherry picking one part of the whole patch, like I 
did here

thanks Mehendran

All issues addressed in this patch have been incorporated or otherwise
fixed in 2.5, specifically __builtins__.filter