BUG #16986: reindex error on ltree index

The following bug has been logged on the website:

Bug reference:      16986
Logged by:          Mauro Valletta
Email address:      mauro@enuan.com
PostgreSQL version: 12.6
Operating system:   Ubuntu 20.04.2
Description:

Hi 
reindexing a table with ltree index this error is thrown:
ERROR:  index row size 7720 exceeds maximum 8152 for index
"ltree_test_session_event_path_idx"
Follow script to reproduce error:
---------------------------------------------------------------
CREATE TABLE "m3_dm"."ltree_test" (
  "session_id" varchar COLLATE "pg_catalog"."default" NOT NULL,
  "session_event_path" "public"."ltree",
  CONSTRAINT "ltree_test_pkey" PRIMARY KEY ("session_id")
);
CREATE INDEX "ltree_test_session_event_path_idx" ON "m3_dm"."ltree_test"
USING gist (
  "session_event_path" "public"."gist_ltree_ops"
);
insert into m3_dm.ltree_test
values (
    'aaa',
    text2ltree(repeat('abcdefghi.',480)||'abcdefghi')
)
;
reindex table m3_dm.ltree_test;
---------------------------------------------

Regards
Mauro