[GSoC] create type questions

Hi mentors and hackers,

I have a new type defined like this
CREATE TYPE thrift_binary (
INPUT = thrift_binary_in,
OUTPUT = thrift_binary_out,
LIKE = bytea
);
in thrift_binary_in, it accepts cstring and returns thrift_binary. And in
this function I returned a bytea because the create type tells the system
thrift_binary and bytea are the same. However, the test passes only when I
explicitly tell thrift_binary_in to return a bytea (change the return type
from thrift_binary to bytea), and it does not work when returns
thrift_binary.
Any ideas why?

Thanks, Charles.