regression test failed on 6.5

Hi,

I'm a newbie and have some questions:

A regression test agaist a new installed 6.5 failed on
items int2, int4 and geometry. It was in Linux 2.0.35.
The posgresql was compiled by:

$ gcc -v
Reading specs from /usr/lib/gcc-lib/i386-pc-linux-gnulibc1/egcs-2.91.66/specs
gcc version egcs-2.91.66 19990314 (egcs-1.1.2 release)

I tried the 6.4.2 before in the same enviroment with the
same compiler. The regression test went 100% ok. However,
I was not able to create a field by int8[] type:

postgres=> create table test (v int8[]);
ERROR: Unable to locate type name '_int8' in catalog

But

postgres=> create table test(v int8);
CREATE
postgres=> drop table test;
DROP
postgres=> create table test(v int4[]);
CREATE

I thought int8 is one of the basic type like int4. Anything
I did wrong? (PS: same error message in 6.5)

Regards,

Min