Another attempt to fix bug mdev-5103.

The earlier pushed fix for the bug was incomplete. It did not remove
the main cause of the problem: the function remove_eq_conds()
removed always true multiple equalities from any conjunct, but did not
adjust the list of them stored in Item_cond_and::cond_equal.current_level.

Simplified the test case for the bug and moved it to another test file.

The fix triggered changes in EXPLAIN EXTENDED for some queries. 

1 files changed, 1 insertions, 1 deletions

diff --git a/mysql-test/r/join_outer.result b/mysql-test/r/join_outer.result
index 284a285dbe3..63d341d1c33 100644
--- a/mysql-test/r/join_outer.result
+++ b/mysql-test/r/join_outer.result
@@ -1773,7 +1773,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	const	PRIMARY,idx	PRIMARY	4	const	1	100.00	
 1	SIMPLE	t2	const	PRIMARY	PRIMARY	4	const	1	100.00	Using index
 Warnings:
-Note	1003	select 5 AS `pk` from `test`.`t2` join `test`.`t1` where ((((1 between 5 and 6) and isnull(5)) or 1)) order by 5
+Note	1003	select 5 AS `pk` from `test`.`t2` join `test`.`t1` where 1 order by 5
 SELECT t1.pk FROM t2 LEFT JOIN t1 ON t2.pk = t1.a
 WHERE t1.b BETWEEN 5 AND 6 AND t1.pk IS NULL OR t1.pk = 5
 ORDER BY t1.pk;