BUG #6718: Cannot delete, create or check existence of extension

The following bug has been logged on the website:

Bug reference:      6718
Logged by:          Gary Haran
Email address:      gary.haran@gmail.com
PostgreSQL version: 9.1.4
Operating system:   OS X
Description:=20=20=20=20=20=20=20=20

development=3D# select version();
                                                                    version=
=20
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
---------------------------------------------------------------------------=
--------------------------------------------------------------------
 PostgreSQL 9.1.4 on x86_64-apple-darwin11.4.0, compiled by Apple clang
version 3.1 (tags/Apple/clang-318.0.61) (based on LLVM 3.1svn), 64-bit
(1 row)

development=3D# create extension hstore;
ERROR:  type "hstore" already exists
development=3D# drop extension hstore;
ERROR:  extension "hstore" does not exist
development=3D# CREATE EXTENSION IF NOT EXISTS hstore;
ERROR:  type "hstore" already exists