BUG #8684: Tables with custom range domain type cannot be analyzed

The following bug has been logged on the website:

Bug reference:      8684
Logged by:          Brett Neumeier
Email address:      bneumeier@gmail.com
PostgreSQL version: 9.3.2
Operating system:   Ubuntu Linux 13.04 64-bit
Description:

In 9.3.2 and master HEAD (3b97e6823b), in a freshly-created postgresql
database (with all tests passing from "make check-world"), this sequence:


-----cut here-----
CREATE DOMAIN range_domain AS tstzrange
    CONSTRAINT exclusive_upper CHECK ((NOT upper_inc(VALUE)))
    CONSTRAINT inclusive_lower CHECK (lower_inc(VALUE));


CREATE TABLE cannot_analyze (
    rng range_domain NOT NULL
);


VACUUM ANALYZE;
-----cut here-----


results in the analyze failing with "ERROR:  type 16385 is not a range type"
rather than succeeding.


(This error is being emitted from range_get_typcache because the result of
lookup_type_cache(rngtypid, TYPECACHE_RANGE_INFO) has a rngelemtype of NULL,
but I haven't tried to figure out why that is or what it should be instead.)