Revert removal of trigger flag from plperl function hash key.REL9_1_ALPHA2

As noted by Jan Urbanski, this flag is in fact needed to ensure that the
function's input/result conversion functions are set up as expected.

Add a regression test to discourage anyone from making same mistake
in future.

1 files changed, 6 insertions, 1 deletions

diff --git a/src/pl/plperl/sql/plperl_trigger.sql b/src/pl/plperl/sql/plperl_trigger.sql
index 1e68759b0f8..c47ddad3ca8 100644
--- a/src/pl/plperl/sql/plperl_trigger.sql
+++ b/src/pl/plperl/sql/plperl_trigger.sql
@@ -128,5 +128,10 @@ FOR EACH ROW EXECUTE PROCEDURE immortal('immortal');
 
 DELETE FROM trigger_test;
 
-
 SELECT * FROM trigger_test;
+
+CREATE FUNCTION direct_trigger() RETURNS trigger AS $$
+    return;
+$$ LANGUAGE plperl;
+
+SELECT direct_trigger();