Issue1775078

These 4 classes have binary op bugs against subclasses that implement their own custom __add__/__radd__/__mul__ etc methods (see the example below)

PyObject._binop_rule calls into the __xxx__/__rxxx__ methods when at least one of the objects involved isn't a built in type. It expects those methods to return Py.NotImplemented when the binary operation doesn't succeed -- signaling that _binop_rule can try a different means (e.g. if __add__ fails, try the other object's __radd__)

The str/unicode/list/tuple methods weren't marked as binary in their .expose files; fixing this ensures that  Py.NotImplemented is automatically returned to _binop_rule when these methods return null.

Some of these methods were taking it upon themselves to incorrectly throw an exception when the bin op failed; doing so short circuits _binop_rule, preventing it from trying different means. These have also been fixed

The methods that did correctly return null would end up (without being defined as a binary op in the expose file) returning a null back into the Python object space, causing evilness such as:

Jython 2.3a0 on java1.5.0_07
Type "copyright", "credits" or "license" for more information.
>>> class Hi(object): 
...     def __radd__(self, o):
...             return '%r + Hi()' % o
... 
>>> a = [1, 2] + Hi()
>>> a
Traceback (innermost last):
  File "<console>", line 1, in ?
NameError: a

This patch also corrects the TypeError messages used when certain binary ops fail; they've been changed to match Python 2.5.1's.

I also added a subclass_binop test to test_descr.py to ensure the return values for + and * ops, and their TypeError messages

List's __iadd__/__imul__ don't have to be defined as binary ops in the .expose file because they don't ever utilize _binop_rule

There's a problem with this change, returning null instead of throwing TypeErrors in the binop methods breaks calling them directly from python, which is expected to work from some tests:

>>> 'abc'.__mul__('') 
NotImplemented

_binop_rule may need to be changed to catch TypeErrors (maybe any python exception) and handle it as if NotImplemented was returned, instead

Actually, returning NotImplemented here is inline with pypy

PyPy 1.0.0 in StdObjSpace on top of Python 2.5.1 (startuptime: 11.98 secs)
>>>> 'abc'.__mul__('')
NotImplemented

The test that fails with this patch applied:

        self.checkraises(TypeError, 'abc', '__mul__', '')

pypy modifies this to:

        self.checkopraises(TypeError, operator.mul, 'abc', '')

which we'd pass

applied in r3461

r3461 also includes that pypy string_test modification I previously mentioned