Bit String expand bug

Hello,
     There's a problem with expanding Bit String data types, it make
right padding with 0 instead of left padding , making  the bit mask
almost useless.
     There is an workaround for that, like mask::bit(n) >>
(n-length(mask)), but is much slower than directly left padding on expand.
     I wonder if is this intended for Big Endian processing or is just
wrong coded.

Have a nice day !