3.0rc3: List of 'os.', 'os.path.' attribute redundencies ... !! ?

IDLE 3.0rc3 (using XP) >>> import os >>> os.altsep '/' >>> os.path.altsep '/' >>> os.curdir '.' >>> os.path.curdir '.' >>> os.defpath '.;C:\\bin' >>> os.path.defpath '.;C:\\bin' >>> os.devnull 'nul' >>> os.path.devnull 'nul' >>> os.pardir '..' >>> os.path.pardir '..' >>> os.pathsep ';' >>> o

3.0rc3: 'os.extsep' gone ... ?

IDLE 2.6 >>> import os >>> os.extsep '.' running XP this result is fine ... ! IDLE 3.0rc3 >>> import os >>> os.extsep Traceback (most recent call last): File "", line 1, in os.extsep AttributeError: 'module' object has no attribute 'extsep' why is this attribute gone in 3.0rc3 ? where is