BUG #14155: bloom index error with unlogged table

The following bug has been logged on the website:

Bug reference: 14155
Logged by: Zhou Digoal
Email address: digoal(at)126(dot)com
PostgreSQL version: 9.6beta1
Operating system: CentOS 6.x x64
Description:

postgres=# create table u_tbl (id int);
CREATE TABLE
postgres=# create index idx_u_tbl on u_tbl using bloom (id);
ERROR: access method "bloom" does not exist
postgres=# create extension bloom;
CREATE EXTENSION
postgres=# create index idx_u_tbl on u_tbl using bloom (id);
CREATE INDEX
postgres=# insert into u_tbl values (1);
INSERT 0 1
postgres=# insert into u_tbl values (2);
INSERT 0 1
postgres=# insert into u_tbl select generate_series(1,100000);
INSERT 0 100000
postgres=# explain select * from u_tbl where id=1;
QUERY PLAN

-----------------------------------------------------------------------------------
Gather (cost=0.00..0.00 rows=0 width=0)
Workers Planned: 1
Single Copy: true
-> Bitmap Heap Scan on u_tbl (cost=1045.38..1397.44 rows=565 width=4)
Recheck Cond: (id = 1)
-> Bitmap Index Scan on idx_u_tbl (cost=0.00..1045.24 rows=565
width=0)
Index Cond: (id = 1)
(7 rows)

postgres=# select * from u_tbl where id=1;
id
----
1
1
(2 rows)

postgres=# drop table u_tbl ;
DROP TABLE
postgres=# create unlogged table u_tbl (id int);
CREATE TABLE
postgres=# create index idx_u_tbl on u_tbl using bloom (id);
ERROR: index "idx_u_tbl" already contains data
postgres=# \set VERBOSITY verbose
postgres=# create index idx_u_tbl on u_tbl using bloom (id);
ERROR: XX000: index "idx_u_tbl" already contains data
LOCATION: blbuildempty, blinsert.c:164
postgres=# drop table u_tbl ;
DROP TABLE
postgres=# create temp table u_tbl (id int);
CREATE TABLE
postgres=# create index idx_u_tbl on u_tbl using bloom (id);
CREATE INDEX
postgres=# insert into u_tbl select generate_series(1,100000);
INSERT 0 100000
postgres=# explain select * from u_tbl where id=1;
QUERY PLAN

-----------------------------------------------------------------------------
Bitmap Heap Scan on u_tbl (cost=1045.38..1397.44 rows=565 width=4)
Recheck Cond: (id = 1)
-> Bitmap Index Scan on idx_u_tbl (cost=0.00..1045.24 rows=565
width=0)
Index Cond: (id = 1)
(4 rows)

postgres=# select * from u_tbl where id=1;
id
----
1
(1 row)