2017-11-02, 00:42
you use the vfs module rather than the extract built-in.
approximately
this works in all versions and for zips as well (with zip:// instead of rar://)
approximately
Code:
import xbmcvfs
xbmcvfs.listdir('rar://<url encoded path to the rar archive>/') to list the contents, then you use
xbmcvfs.copy('rar://<urlencoded path to the rar archive>/<file in archive'>, subdir'+/'+<file in archive>)