Inconsistent shift operator

The below test cases show the obvious inconsistency between different
integer types.

Regards,

Roman

test=# \t
Showing only tuples.
test=# select 1::int2 << 17;
         0

test=# select 1::int4 << 33;
         2

test=# select 1::int8 << 65;
         2

test=# select 2::int2 >> 17;
         0

test=# select 2::int4 >> 33;
         1

test=# select 2::int8 >> 65;
         1