WL#5370 Keep forward-compatibility when changing

        'CREATE TABLE IF NOT EXISTS ... SELECT' behaviour
BUG#47132, BUG#47442, BUG49494, BUG#23992 and BUG#48814 will disappear
automatically after the this patch.
BUG#55617 is fixed by this patch too.
            
This is the 5.5 part.
It implements:
- 'CREATE TABLE IF NOT EXISTS ... SELECT' statement will not insert
  anything and binlog anything if the table already exists.
  It only generate a warning that table already exists.
- A couple of test cases for the behavior changing.

1 files changed, 1 insertions, 1 deletions

diff --git a/mysql-test/t/union.test b/mysql-test/t/union.test
index ab2745ceeef..93dc4cad50c 100644
--- a/mysql-test/t/union.test
+++ b/mysql-test/t/union.test
@@ -253,7 +253,7 @@ SELECT * FROM t1 UNION SELECT * FROM t2 ORDER BY a desc LIMIT 1;
 
 create temporary table t1 select a from t1 union select a from t2;
 drop temporary table t1;
---error 1093
+--error ER_TABLE_EXISTS_ERROR
 create table t1 select a from t1 union select a from t2;
 --error 1054
 select a from t1 union select a from t2 order by t2.a;