Overriding default arguments for all command fails

[hirenvadalia]

As mentioned in https://amoffat.github.io/sh/sections/default_arguments.html#default-arguments, overriding default arguments for all further command fails as below:

>>> import sh
>>> from io import StringIO
>>> buf = StringIO()
>>> sh2 = sh(_out=buf)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/site-packages/sh.py", line 3367, in __call__
    code = parent[4][0].strip()
TypeError: 'NoneType' object has no attribute '__getitem__'
>>> 

And after adding below two line at 3368 (after parent = inspect.stack()[1]) it worked:

if parent[4] is None:
    return new_mod

[guyskk]

I meet the same error:

>>> import sh
>>> from io import StringIO
>>> 
>>> buf = StringIO()
>>> sh2 = sh(_out=buf)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/guyskk/.pyenv/versions/rssant/lib/python3.6/site-packages/sh.py", line 3367, in __call__
    code = parent[4][0].strip()
TypeError: 'NoneType' object is not subscriptable
>>> 
>>> sh.__version__
'1.12.14'

Python version Python 3.6.6
OS Linux archlinux 4.17.4-1-ARCH #1 SMP PREEMPT Tue Jul 3 15:45:09 UTC 2018 x86_64 GNU/Linux

[amoffat]

#466 fixes this and will go out with the next release.