Should isinstance(newint(...), int) return True for Python 2 when value is inside int bounds?

[posita]

Consider the following on PyPy (which uses a pure python version of datetime):

Python 2.7.10 (f3ad1e1e1d6215e20d34bb65ab85ff9188c9f559, Sep 04 2015, 05:13:03)
[PyPy 2.6.1 with GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>> import datetime
>>>> datetime.__file__
'/.../lib/pypy/lib_pypy/datetime.pyc'
>>>> from builtins import int as _int
>>>> i = int(1431216000)
>>>> j = long(i)
>>>> k = _int(i)
>>>> isinstance(i, int)
True
>>>> isinstance(i, long)
False
>>>> isinstance(j, int)
False
>>>> isinstance(j, long)
True
>>>> isinstance(k, int)
False
>>>> isinstance(k, long)
True
>>>> datetime.timedelta(seconds=i)
datetime.timedelta(16565)
>>>> datetime.timedelta(seconds=j)
datetime.timedelta(16565)
>>>> datetime.timedelta(seconds=k)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/.../lib/pypy/lib_pypy/datetime.py", line 491, in __new__
    assert isinstance(s, int)
AssertionError

This, of course, can be worked around using:

>>>> from future.utils import native
>>>> datetime.timedelta(seconds=native(k))
datetime.timedelta(16565)

This does not happen on cPython, which uses a C implementation of datetime:

Python 2.7.10 (default, Sep 24 2015, 10:13:45)
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import datetime
>>> datetime.__file__
'/.../lib/python2.7/lib-dynload/datetime.so'
>>> from builtins import int as _int
>>> i = int(1431216000)
>>> j = long(i)
>>> k = _int(i)
>>> isinstance(i, int)
True
>>> isinstance(i, long)
False
>>> isinstance(j, int)
False
>>> isinstance(j, long)
True
>>> isinstance(k, int)
False
>>> isinstance(k, long)
True
>>> datetime.timedelta(seconds=i)
datetime.timedelta(16565)
>>> datetime.timedelta(seconds=j)
datetime.timedelta(16565)
>>> datetime.timedelta(seconds=k)
datetime.timedelta(16565)

I'm not sure whether this is a problem with PyPy datetime.py, or future or something else, but it got me to thinking. What if isinstance(newint(x), int) evaluated to True iff x <= sys.maxint and x >= (-sys.maxint - 1)? Would that be absurd or break things? It is, after all, called int, but behaves exclusively like a long with respect to the above context in Python 2.

[posita]

See also:

• https://bugs.python.org/issue25714
• https://bitbucket.org/pypy/pypy/issues/2193/datetimetimedelta-chokes-on-seconds

However, even if these are fixed, having isinstance(newint(...), int) return True when in range may avoid similar problems elsewhere.