isinstance(..., str) fails when applied to elements of sys.argv

[maxalbert]

This bug is related to the issues with isinstance(..., str) described here.

The following works in Python 2.7:

from __future__ import unicode_literals
from builtins import str

assert isinstance('some string', str)

However, the following fails (also in Python 2.7):

from __future__ import unicode_literals
from builtins import str
import sys

assert isinstance(sys.argv[0], str)

The reason is that elements of sys.argv are still instances of the original type str, not of future.types.newstr.newstr. This makes working with command line arguments tricky in legacy Py2 code that is being upgraded for Py2/Py3 compatibility using python-future.

For the record, both code snippets above work as expected in Python 3.4.

[jmadler]

Would it work to add sys.argv = [str(x) for x in sys.argv] to src/builtins/__init__.py?