Fix path split for single quotes.

[adiroiban]

Scope

This fix a critical bug in which path containing single quotes are not handled corretly.

The single quote is replaced for a path separator.

For example, with the old code a path line

/some/O`Reilly/file

was converted in 

/some/O/Reilly/file

Changes

Update the path split code and simplify it with explicit regrex escaping.

I have no idea why I have used %r there.

How to try and test the changes

reviewers: @danuker

Check that changes make sense.

For now this is a quick fix as this is urgent

In the future we should start using https://hypothesis.readthedocs.io/en/latest/index.html for unit testing in this low level libraries so that we can generate all possible characters and make sure path splinting works for them.

[codecov[bot]]

Codecov Report

Merging #105 (6c390a0) into master (1f6af3b) will decrease coverage by 1.41%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #105      +/-   ##
==========================================
- Coverage   89.52%   88.10%   -1.42%     
==========================================
  Files          61       61              
  Lines        7914     7920       +6     
  Branches      652      652              
==========================================
- Hits         7085     6978     -107     
- Misses        642      738      +96     
- Partials      187      204      +17     

Impacted Files	Coverage Δ
chevah/compat/tests/elevated/test_system_users.py	91.26% <ø> (-3.18%)	:arrow_down:
chevah/compat/posix_filesystem.py	92.99% <100.00%> (-0.43%)	:arrow_down:
chevah/compat/tests/normal/test_filesystem.py	97.92% <100.00%> (-0.92%)	:arrow_down:
chevah/compat/tests/normal/test_capabilities.py	79.45% <0.00%> (-17.30%)	:arrow_down:
chevah/compat/tests/elevated/__init__.py	80.95% <0.00%> (-9.53%)	:arrow_down:
chevah/compat/capabilities.py	63.15% <0.00%> (-7.90%)	:arrow_down:
chevah/compat/helpers.py	53.33% <0.00%> (-6.67%)	:arrow_down:
chevah/compat/administration.py	67.02% <0.00%> (-5.14%)	:arrow_down:
chevah/compat/nt_capabilities.py	85.15% <0.00%> (-4.69%)	:arrow_down:
... and 6 more