Sort exception when file not writable

[lowell80]

The problem

Unandled exception if ksconf sort -i runs against a file that can't be updated.

Environment

• Ksconf version: 0.7.2
• OS & version used: Amazon Linux
• Python version: 2.7
• Installed via: pip via pre-commit

Details

$ ksconf --version
 _                         __
| |                       / _|
| | _____  ___ ___  _ __ | |_
| |/ / __|/ __/ _ \| '_ \|  _|
|   <\__ \ (_| (_) | | | | |
|_|\_\___/\___\___/|_| |_|_|

ksconf 0.7.2  (Build 341)
Python: 2.7.14  (/usr/bin/python2)
Git SHA1 c1923770 committed on 2019-03-22
Installed at: /usr/lib/python2.7/site-packages/ksconf
Written by Lowell Alleman <lowell@kintyre.co>.
Copyright (c) 2019 Kintyre Solutions, Inc, all rights reserved.
Licensed under Apache Public License v2

  kintyre_splunk_conf  (0.7.2)

    Commands:
      check           (stable)    OK
      combine         (beta)      OK
      diff            (stable)    OK
      filter          (alpha)     OK
      merge           (stable)    OK
      minimize        (beta)      OK
      promote         (beta)      OK
      rest-export     (beta)      OK
      rest-publish    (alpha)     OK
      snapshot        (alpha)     OK
      sort            (stable)    OK
      unarchive       (beta)      OK

Example Traceback:

Traceback (most recent call last):
  File "/opt/splunk/.cache/pre-commit/repo35FeDP/py_env-python2/bin/end-of-file-fixer", line 10, in <module>
    sys.exit(end_of_file_fixer())
  File "/opt/splunk/.cache/pre-commit/repo35FeDP/py_env-python2/lib/python2.7/site-packages/pre_commit_hooks/end_of_file_fixer.py", line 58, in end_of_file_fixer
    with open(filename, 'rb+') as file_obj:
IOError: [Errno 13] Permission denied: 'MYORG_props/default/app.conf'

Steps To Reproduce Issue

1. Make file read-only
2. Run ksconf sort -i on it.

[lowell80]

Workaround:

find -name '*.conf' -o -name '*.meta' | xargs chmod +w

[lowell80]

Desired behavior:

1. IOError should be trapped and not handled as an unhandled exception. The error should be written to stderr; and if multiple inputs files were given, it should continue with the others.
2. This error should be classified as an "Error" and reported as such in the output summary screen. (In other words, it should be listed alongside of files that were modified or unchanged.)
3. We must ensure that exit code is non-0 when an errors occurs. (Create a new exit code, if none of them currently fit). This is critical for pre-commit and other scripting uses of ksconf.