[pypy-issue] Issue #2343: PyPy hides TypeError raised by __instancecheck__ (pypy/pypy)

[Michael Amrhein]

New issue 2343: PyPy hides TypeError raised by __instancecheck__
https://bitbucket.org/pypy/pypy/issues/2343/pypy-hides-typeerror-raised-by

Michael Amrhein:


```
#!python

Python 2.7.10 (7e8df3df96417c16c2d55b41352ec82c9c69c978, Jul 09 2016, 13:13:39)
[PyPy 5.3.1 with GCC 4.9.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>> class AnyMeta(type):
....     def __instancecheck__(cls, obj):
....         raise TypeError("'Any' cannot be used with isinstance().")
....         
>>>> class Any(object):
....     __metaclass__ = AnyMeta
.... 
>>>> Any.__instancecheck__(42)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 3, in __instancecheck__
TypeError: 'Any' cannot be used with isinstance().

```
but

```
#!python

>>>> isinstance(42, Any)
False

```