Like os.walk, except that:
        a) directories listed in exclude_dir are excluded with all
          their subdirectories
        b) absolute paths are returned

def make_srcdir_list(self,exclude_dirs):
        """
        Like os.walk, except that:
        a) directories listed in exclude_dir are excluded with all
          their subdirectories
        b) absolute paths are returned
        """
        srcdir_list = []
        for topdir in self.topdirs:
            srcdir_list.append(topdir)
            srcdir_list += self.recursive_dir_list(topdir,exclude_dirs)
        return srcdir_list