bug#33094: Error in upgrading from 5.0 to 5.1 when table contains
triggers
and
#41385: Crash when attempting to repair a #mysql50# upgraded table
with triggers.

Problem:
1. trigger code didn't assume a table name may have
a "#mysql50#" prefix, that may lead to a failing ASSERT().
2. "ALTER DATABASE ... UPGRADE DATA DIRECTORY NAME" failed
for databases with "#mysql50#" prefix if any trigger.
3. mysqlcheck --fix-table-name didn't use UTF8 as a default
character set that resulted in (parsing) errors for tables with
non-latin symbols in their names and definitions of triggers.

Fix:
1. properly handle table/database names with "#mysql50#" prefix.
2. handle --default-character-set mysqlcheck option;
if mysqlcheck is launched with --fix-table-name or --fix-db-name
set default character set to UTF8 if no --default-character-set
option given.

Note: if given --fix-table-name or --fix-db-name option,
without --default-character-set mysqlcheck option
default character set is UTF8.

The next number (AUTO_INCREMENT) field of the table for write
rows events are not initialized, and cause some engines (innodb)
not correctly update the tables's auto_increment value.

This patch fixed this problem by honor next number fields if present.

   41776 type_date.test may fail if run around midnight.
into GCA tree.

   41111 events_bugs fails sporadically on pushbuild
into GCA tree

41932 funcs_1: is_collation_character_set_applicability path too long for tar
into GCA tree

+ add workaround for bug 38124
+ messages into the protocol when sessions are switched
+ replace error numbers by error names
+ reset of system variables to initial values per subtest
+ remove a file created by this test
+ minor improvements in structure and formatting

Added cleanup of status variables to the end of binlog_database.
Re-recorded .result file to account for cleanup statement.
NOTE:  binlog.binlog_innodb also has had an FLUSH STATUS; statement added to it as well, but
adding this cleanup as a preventative measure.

Bug#36428: MY_MUTEX_INIT_FAST is used before initialization

On some thread implementations, we need a fake mutex attri-
bute as a placeholder, which we define as a global variable,
"my_fast_mutexattr".  Well. that must be initialized before 
used in any mutexes, and the ordering of initializations in 
the API function  my_init()  was wrong.

Now, put my_thread_global_init(), which initializes the attri-
butes that mutexes require.

Bounds-checks and blocksize corrections were applied to user-input,
but constants in the server were trusted implicitly. If these values
did not actually meet the requirements, the user could not set change
a variable, then set it back to the (wonky) factory default or maximum
by explicitly specifying it (SET <var>=<value> vs SET <var>=DEFAULT).

Now checks also apply to the server's presets. Wonky values and maxima
get corrected at startup. Consequently all non-offsetted values the user
sees are valid, and users can set the variable to that exact value if
they so desire.

2. Avoid bad effects of bug 41925 Warning 1366 Incorrect string value:
                                  ...  for column processlist.info
3. Add poll routines which ensure that subtests meet stable scenarios.
   This does not change the sense of the subtests.

post push fix, added test found a valgrind warning

Adding comments to some of the high-level functions in replication.

No need to mask the error code returned by getting the next row to end of file when
doing filesort.

When substituting system constant functions with a constant result
the server was not expecting that the function may return NULL.
Fixed by checking for NULL and returning Item_null (in the relevant
collation) if the result of the system constant function was NULL.

The special TRUNCATE TABLE (DDL) transaction wasn't being properly
rolled back if a error occurred during row by row deletion. The
error can be caused by a foreign key restriction imposed by InnoDB
SE and would cause the server to erroneously issue a implicit
commit.

The solution is to rollback the transaction if a truncation via row
by row deletion fails, otherwise commit. All effects of a TRUNCATE 
ABLE operation are rolled back if a row by row deletion fails.

Problem: when the server reads a log_event from file, it should read
the post-header lengths from the format_description_log_event. Some
event types which currently have post-header length 0 did not do this,
and instead had a hard-coded zero length for the post-header. That
means the current server version will not be able to read future
versions of these events.
Fix: make the reader functions read the post-header.

The problem is that a mysql connection instance is not thread-safe
and reentrant, meaning that it can't be used concurrently and can't
be re-entered while it's already running. This applies for any form
of the server (embedded or not), but this rule can be violated in a
test case if the test sends a new command without waiting for the
result of previous command that was sent asynchronously and this can
lead to hangs when over a network or to crashes under embedded server
as the server query execution path will be re-entered concurrently
with the same connection structure.

The solution is to rework the test case so that the aforementioned
rule is obeyed.

Passing dubious "year zero" in non-zero date (not "0000-00-00") could
lead to negative value for year internally, while variable was unsigned.
This led to Really Bad Things further down the line.

Now doing calculations with signed type for year internally.