Follow the rule that regression-test-created roles are named "regress_xxx".

contrib/amcheck didn't get the memo either.

contrib/amcheck/expected/check_btree.out

@@ -5,9 +5,9 @@ INSERT INTO bttest_a SELECT * FROM generate_series(1, 100000);
 INSERT INTO bttest_b SELECT * FROM generate_series(100000, 1, -1);
 CREATE INDEX bttest_a_idx ON bttest_a USING btree (id);
 CREATE INDEX bttest_b_idx ON bttest_b USING btree (id);
-CREATE ROLE bttest_role;
+CREATE ROLE regress_bttest_role;
 -- verify permissions are checked (error due to function not callable)
-SET ROLE bttest_role;
+SET ROLE regress_bttest_role;
 SELECT bt_index_check('bttest_a_idx'::regclass);
 ERROR:  permission denied for function bt_index_check
 SELECT bt_index_parent_check('bttest_a_idx'::regclass);
@@ -16,9 +16,9 @@ RESET ROLE;
 -- we, intentionally, don't check relation permissions - it's useful
 -- to run this cluster-wide with a restricted account, and as tested
 -- above explicit permission has to be granted for that.
-GRANT EXECUTE ON FUNCTION bt_index_check(regclass) TO bttest_role;
-GRANT EXECUTE ON FUNCTION bt_index_parent_check(regclass) TO bttest_role;
-SET ROLE bttest_role;
+GRANT EXECUTE ON FUNCTION bt_index_check(regclass) TO regress_bttest_role;
+GRANT EXECUTE ON FUNCTION bt_index_parent_check(regclass) TO regress_bttest_role;
+SET ROLE regress_bttest_role;
 SELECT bt_index_check('bttest_a_idx');
  bt_index_check 
 ----------------
@@ -88,5 +88,5 @@ COMMIT;
 -- cleanup
 DROP TABLE bttest_a;
 DROP TABLE bttest_b;
-DROP OWNED BY bttest_role; -- permissions
-DROP ROLE bttest_role;
+DROP OWNED BY regress_bttest_role; -- permissions
+DROP ROLE regress_bttest_role;

contrib/amcheck/sql/check_btree.sql

@@ -8,10 +8,10 @@ INSERT INTO bttest_b SELECT * FROM generate_series(100000, 1, -1);
 CREATE INDEX bttest_a_idx ON bttest_a USING btree (id);
 CREATE INDEX bttest_b_idx ON bttest_b USING btree (id);
 
-CREATE ROLE bttest_role;
+CREATE ROLE regress_bttest_role;
 
 -- verify permissions are checked (error due to function not callable)
-SET ROLE bttest_role;
+SET ROLE regress_bttest_role;
 SELECT bt_index_check('bttest_a_idx'::regclass);
 SELECT bt_index_parent_check('bttest_a_idx'::regclass);
 RESET ROLE;
@@ -19,9 +19,9 @@ RESET ROLE;
 -- we, intentionally, don't check relation permissions - it's useful
 -- to run this cluster-wide with a restricted account, and as tested
 -- above explicit permission has to be granted for that.
-GRANT EXECUTE ON FUNCTION bt_index_check(regclass) TO bttest_role;
-GRANT EXECUTE ON FUNCTION bt_index_parent_check(regclass) TO bttest_role;
-SET ROLE bttest_role;
+GRANT EXECUTE ON FUNCTION bt_index_check(regclass) TO regress_bttest_role;
+GRANT EXECUTE ON FUNCTION bt_index_parent_check(regclass) TO regress_bttest_role;
+SET ROLE regress_bttest_role;
 SELECT bt_index_check('bttest_a_idx');
 SELECT bt_index_parent_check('bttest_a_idx');
 RESET ROLE;
@@ -57,5 +57,5 @@ COMMIT;
 -- cleanup
 DROP TABLE bttest_a;
 DROP TABLE bttest_b;
-DROP OWNED BY bttest_role; -- permissions
-DROP ROLE bttest_role;
+DROP OWNED BY regress_bttest_role; -- permissions
+DROP ROLE regress_bttest_role;