MDEV-4440 IF NOT EXISTS in multi-action ALTER does not work when the problem is created by a previous part of the ALTER.

        Loops added to the handle_if_exists_option() to check the
        CREATE/DROP lists for duplicates.

1 files changed, 10 insertions, 0 deletions

diff --git a/mysql-test/t/alter_table.test b/mysql-test/t/alter_table.test
index 4aeabf5f349..416c73009e6 100644
--- a/mysql-test/t/alter_table.test
+++ b/mysql-test/t/alter_table.test
@@ -1314,6 +1314,16 @@ ALTER TABLE t2 DROP FOREIGN KEY IF EXISTS t2_ibfk_1;
 SHOW CREATE TABLE t2;
 
 DROP TABLE t2;
+CREATE TABLE t2 (
+  id INT(11) NOT NULL);
+ALTER TABLE t2 ADD COLUMN a INT, ADD COLUMN IF NOT EXISTS a INT;
+ALTER TABLE t2 ADD KEY k_id(id), ADD KEY IF NOT EXISTS k_id(id);
+SHOW CREATE TABLE t2;
+ALTER TABLE t2 DROP KEY k_id, DROP KEY IF EXISTS k_id;
+ALTER TABLE t2 DROP COLUMN a, DROP COLUMN IF EXISTS a;
+SHOW CREATE TABLE t2;
+
+DROP TABLE t2;
 DROP TABLE t1;
 
 --echo # Bug#11748057 (formerly known as 34972): ALTER TABLE statement doesn't