BUG #3765: strange results for bit string hex notation cast to bit

The following bug has been logged online:

Bug reference:      3765
Logged by:          Cade Cairns
Email address:      cadec@otii.com
PostgreSQL version: 8.1.10
Operating system:   Mac OS X 10.5.1
Description:        strange results for bit string hex notation cast to bit
Details:

When casting a bit string constant using hexadecimal notation to a longer
bit string, the result is padded with 0's on the right. This will result in
inconsistent/useless results:

test=# select x'ff'::integer;
 int4
------
  255
(1 row)

test=# select x'ff'::bit(16)::integer;
 int4
-------
 65280
(1 row)