NULL MERGE this to 5.1

Apply the following InnoDB snapshots:
innodb-5.0-ss1319
innodb-5.0-ss1331
innodb-5.0-ss1333
innodb-5.0-ss1341

Fixes:
- Bug #21409: Incorrect result returned when in READ-COMMITTED with query_cache ON
  At low transaction isolation levels we let each consistent read set
  its own snapshot.
- Bug #23666: strange Innodb_row_lock_time_% values in show status; also millisecs wrong
  On Windows ut_usectime returns secs and usecs relative to the UNIX
  epoch (which is Jan, 1 1970).

- Bug #25494: LATEST DEADLOCK INFORMATION is not always cleared
  lock_deadlock_recursive(): When the search depth or length is exceeded,
  rewind lock_latest_err_file and display the two transactions at the
  point of aborting the search.

- Bug #25927: Foreign key with ON DELETE SET NULL on NOT NULL can crash server
  Prevent ALTER TABLE ... MODIFY ... NOT NULL on columns for which
  there is a foreign key constraint ON ... SET NULL.

- Bug #26835: Repeatable corruption of utf8-enabled tables inside InnoDB
  The bug could be reproduced as follows:

  Define a table so that the first column of the clustered index is
  a VARCHAR or a UTF-8 CHAR in a collation where sequences of bytes
  of differing length are considered equivalent.

  Insert and delete a record.  Before the delete-marked record is
  purged, insert another record whose first column is of different
  length but equivalent to the first record.  Under certain conditions,
  the insertion can be incorrectly performed as update-in-place.

  Likewise, an operation that could be done as update-in-place can
  unnecessarily be performed as delete and insert, but that would not
  cause corruption but merely degraded performance.

1 files changed, 18 insertions, 0 deletions

diff --git a/mysql-test/r/innodb.result b/mysql-test/r/innodb.result
index 99f0d4100ee..0638152ba42 100644
--- a/mysql-test/r/innodb.result
+++ b/mysql-test/r/innodb.result
@@ -2968,3 +2968,21 @@ a
 drop table t2, t1;
 create table t1 (g geometry not null, spatial gk(g)) engine=innodb;
 ERROR HY000: The used table type doesn't support SPATIAL indexes
+CREATE TABLE t1 (a INT, INDEX(a)) ENGINE=InnoDB;
+CREATE TABLE t2 (a INT, INDEX(a)) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1);
+INSERT INTO t2 VALUES (1);
+ALTER TABLE t2 ADD FOREIGN KEY (a) REFERENCES t1 (a) ON DELETE SET NULL;
+ALTER TABLE t2 MODIFY a INT NOT NULL;
+ERROR HY000: Error on rename of '#sql-temporary' to './test/t2' (errno: 150)
+DELETE FROM t1;
+DROP TABLE t2,t1;
+CREATE TABLE t1 (a VARCHAR(5) COLLATE utf8_unicode_ci PRIMARY KEY)
+ENGINE=InnoDB;
+INSERT INTO t1 VALUES (0xEFBCA4EFBCA4EFBCA4);
+DELETE FROM t1;
+INSERT INTO t1 VALUES ('DDD');
+SELECT * FROM t1;
+a
+DDD
+DROP TABLE t1;