Permissions for deleting files

[GoogleCodeExporter]

pyfakefs doesn't seem to honor permissions when deleting files. I marked a 
directory and the files contained within as read-only using the fake_os 
module's chmod function, but os.remove and shutil.rmtree were able to remove 
the files without issue.

What steps will reproduce the problem?
# Create filesystem with '/dir1/file1'

path = os.path.join('dir1', 'file1')
mode = self.fake_os.stat(path)[stat.ST_MODE]
self.fake_os.chmod('dir1', 0444)
self.fake_os.chmod(path, 0444)
self.fake_os.remove(path)

What is the expected output? What do you see instead?
I would expect an "OSError: [Errno 13] Permission denied" or equivalent, 
instead the file is removed.

What version of the product are you using? On what operating system?
pyfakefs 2.4, tested on Windows 7 and Red Hat 6

Please provide any additional information below.
It would be really helpful to acknowledge permissions, since many tests I write 
are around "how does my program behave if it doesn't have access to the 
necessary files?"

Original issue reported on code.google.com by londinop on 28 Feb 2014 at 5:02

[mrbean-bremen]

Related Windows specific problem: under Windows, it is not possible to delete an open file. This is also not handled by pyfakefs.