exec_eval_simple_expr() needs to do CommandCounterIncrement() not just

GetTransactionSnapshot() to ensure ActiveSnapshot advances properly.
Sigh.  Extend regression test so it reveals this error too.

2 files changed, 14 insertions, 0 deletions

diff --git a/src/test/regress/expected/plpgsql.out b/src/test/regress/expected/plpgsql.out
index 1f11bbb75c9..10df82cfc24 100644
--- a/src/test/regress/expected/plpgsql.out
+++ b/src/test/regress/expected/plpgsql.out
@@ -2089,5 +2089,17 @@ select sp_add_user('user2');
           -1
 (1 row)
 
+select sp_add_user('user3');
+ sp_add_user 
+-------------
+           3
+(1 row)
+
+select sp_add_user('user3');
+ sp_add_user 
+-------------
+          -1
+(1 row)
+
 drop function sp_add_user(text);
 drop function sp_id_user(text);
diff --git a/src/test/regress/sql/plpgsql.sql b/src/test/regress/sql/plpgsql.sql
index 48618b95085..62aa3543479 100644
--- a/src/test/regress/sql/plpgsql.sql
+++ b/src/test/regress/sql/plpgsql.sql
@@ -1802,6 +1802,8 @@ end$$ language plpgsql;
 select sp_add_user('user1');
 select sp_add_user('user2');
 select sp_add_user('user2');
+select sp_add_user('user3');
+select sp_add_user('user3');
 
 drop function sp_add_user(text);
 drop function sp_id_user(text);