BUG #6524: lpermission denied to create extension "ltree". Must be superuser to create this extension.

The following bug has been logged on the website:

Bug reference:      6524
Logged by:          naox
Email address:      spamik@yum.pl
PostgreSQL version: 9.1.3
Operating system:   linux
Description:=20=20=20=20=20=20=20=20

CREATE EXTENSION ltree;
ERROR:  permission denied to create extension "ltree"
HINT:  Must be superuser to create this extension.

Why does ltree require superuser privledge? Is it dangerous and allow
circumventing server security? No mention of this in manual so it is either
documentation problem or a too strict check problem.