The problem was that doing ALTER TABLE on a table which had a key
on a TEXT/BLOB column with a prefix longer than the maximum number
of characteres in this column (as per the character set), by mistake,
caused an error (Error 1170 - ER_BLOB_KEY_WITHOUT_LENGTH).

This bug not repeatable in 5.5.

This patch adds a regression test to alter_table.test and
contains no code changes.

Remove last traces of HAVE_NDBCLUSTER_DB define - it has not had an effect in a long time and is just confusing.
At the same time backport the removal of OPT_NDB_CONNECTSTRING and OPT_NDBCLUSTER values from "enum options_client"

               ("-") IN DATABASE NAMES IN ALTER DATABASE.

mysqldump did not quote database name in 'ALTER DATABASE'
statements in its output. This can further cause a failure
while loading if database name contains a hyphen '-'.

This happened as, while printing the 'ALTER DATABASE'
statements, the database name was not quoted.

Fixed by quoting the database name.

A separate fix for 5.1 (as 5.1 and 5.5 have seriously
differged in the related pieces of the code).
A patch for 5.5 was approved earlier.

Problem: ucs2 was correctly disallowed in "SET NAMES" only,
while mysql_real_connect() and mysql_change_user() still allowed
to use ucs2, which made server crash.

Fix: disallow ucs2 in mysql_real_connect() and mysql_change_user().

  @ sql/sql_priv.h
    - changing return type for thd_init_client_charset() to bool,
      to return errors to the caller

  @ sql/sql_var.cc
    - using new function

  @ sql/sql_connect.cc
    - thd_client_charset_init:
      in case of unsupported client character set send error and return true;
      in case of success return false
    - check_connection:
      Return error if character set initialization failed

  @ sql/sql_parse.cc
    - check charset in the very beginnig of the CMD_CHANGE_USER handling code

  @ tests/mysql_client_test.c
    - adding tests

The loop that was looping over subqueries' references to outer field used a
local boolean variable to tell whether the field was grouped or not. But the
implementor failed to reset the variable after each iteration. Thus a field
that was not directly aggregated appeared to be.

Fixed by resetting the variable upon each new iteration.

Problem: ucs2 was correctly disallowed in "SET NAMES" only,
while mysql_real_connect() and mysql_change_user() still allowed
to use ucs2, which made server crash.

Fix: disallow ucs2 in mysql_real_connect() and mysql_change_user().

  @ sql/set_var.cc
    Using new function.

  @ sql/sql_acl.cc
    - Return error if character set initialization failed
    - Getting rid of pointer aliasing:
      Initialize user_name to NULL, to avoid double free().

  @ sql/sql_connect.cc
    - in case of unsupported client character set send error and return true
    - in case of success return false

  @ sql/sql_connect.h
    - changing return type for thd_init_client_charset() to bool,
      to return errors to the caller

  @ sql/sql_parse.h
    - introducing a new function, to reuse in all places where we need
    to check client character set.

  @ tests/mysql_client_test.c
    Adding test

MONTHNAME(0) claims that it is about to return NOT NULL
value, whereas it actually returns NULL.

As a result storage_engine variable (which cannot be NULL)
protection was bypassed and NULL value was accepted, causing
server crash.

Fixed MONTHNAME(0) to report valid NULL flag.

      
Problem:
  IF() did not copy collation derivation and repertoire from
  an argument if the opposite argument was NULL:
    IF(cond, res1, NULL)
    IF(cond, NULL, res2)
  only CHARSET_INFO pointer was copied.
  This resulted in illegal mix of collations error.

Fix:
  copy all collation parameters from the non-NULL argument:
  CHARSET_INFO pointer, derivation, repertoire.

Thanks to Kristian Nielsen for finding out the root cause for the
failure, see: https://bugs.launchpad.net/maria/+bug/677407

          memory reference

There are two issues present here.
  1) There is a possibility that we test a byte beyond the
     allocated buffer

  2) We compare a byte that might never have been
     initalized to see if it's 0.

The first issue is not triggered by existing code, but an
ASSERT has been added to safe-guard against introducing
new code that triggers it.

The second issue is what triggers the Valgrind warnings
reported in the bug report. A buffer is allocated in
class String to hold the value. This buffer is populated
by the character data constituting the string, but is not
zero-terminated in most cases.  Testing if it is indeed
zero-terminated means that we check a byte that has never
been explicitly set, thus causing Valgrind to trigger.

Note that issue 2 is not a serious problem.  The variable
is read, and if it's not zero, we will set it to zero.
There are no further consequences.

Note that this patch does not fix the underlying problems
with issue 1, as it is deemed too risky to fix at this
point (as noted in the bug report).  As discussed in
the report, the c_ptr() method should probably be
replaced, but this requires a thorough analysis of the
~200 calls to the method.

With --mem if fails with
+UNEXPECTED ERROR NUMBER: 1290

In var/log/mysqld.2.err we have:
[ERROR] LOAD DATA INFILE in the slave SQL Thread can only read from --slave-load-tmpdir. Please, report a bug.
[ERROR] Slave SQL: Error 'The MySQL server is running with the --slave-load-tmpdir option so it cannot execute this statement' on query. Default database: 'test'. Query: 'LOAD DATA INFILE '../../tmp/SQL_LOAD-2-1-1.data' INTO  TABLE `t1` FIELDS TERMINATED BY '\t' ENCLOSED BY '' ESCAPED BY '\\' LINES TERMINATED BY '\n' (`a`, `b`)', Error_code: 1290

getcwd() in the server yields something like: /dev/shm/var_auto_iv5Q/mysqld.2/data

No conflicts

Assertion `bitmap_is_set_all(&table->s->all_set)' failed in
handler::ha_reset

This followup fixes the compilation warning
  'test_bit' may be used uninitialized in this function
introduced by the previous patch.