BUG #13711: Error creating index on ltree column

The following bug has been logged on the website:

Bug reference: 13711
Logged by: Cstdenis
Email address: cstdenis(at)ctgameinfo(dot)com
PostgreSQL version: 9.2.13
Operating system: FreeBSD 10.1
Description:

CREATE INDEX user_comments_id_tree ON user_comments USING gist (id_tree);

ERROR: failed to add item to index page in "user_comments_id_tree"
SQL state: XX000

I have another database with identical schema with no problems, but when I
try to restore the backup of this one on a new server the restore has this
error with 2 indexes on this column.

Some info about the data:

fanart_central=# Select count(id_tree) from user_comments;
count
---------
6650726
(1 row)

fanart_central=# Select max(nlevel(id_tree)) from user_comments;
max
-----
183
(1 row)

fanart_central=# Select max(bit_length(ltree2text(id_tree))),
max(char_length(ltree2text(id_tree))) from user_comments;
max | max
-------+------
11704 | 1463
(1 row)

Table definition:
CREATE TABLE user_comments
(
comment_id serial NOT NULL,
<snip>
-- Inherited from table base_comments: id_tree ltree NOT NULL DEFAULT
''::ltree
)
INHERITS (base_comments)