Part of bzrlib.tests
Files which are created underneath .bzr/ should inherit its permissions. So if the directory is group writable, the files and subdirs should be as well.
In the future, when we have Repository/Branch/Checkout information, the permissions should be inherited individually, rather than all be the same.
|Function||chmod_r||Recursively chmod from a base directory|
|Function||check_mode_r||Check that all permissions match|