baseDir should accept absolute paths?

[emilekberg]

If processing multiple css files at the same time, in different folders, and i store all my fonts/images in a common folder, i cannot setup the basedir properly, since it will always be relative from the currently processed css.

Is this intended? in my case, i cannot pass any value that would process all files, wherever they are located in a common folder, without a common relative path to them.