shutil.copy failure when the destination already exists and is read-only
<p>I am using shutil.copy to copy files from one location to another.  If a file with the same name already exists in the destination location, it is normally ok and overwrites.  However, if the destination is read-only, it throws a permission denied error.</p>

<p>What is the most elegant way to deal with this?  Is there another shutil function that will deal with the permissions issue, or must I check the permissions on ever file I copy?</p>
