This assertion would occur if UPDATE was used to update multiple
tables containing an AUTO_INCREMENT column and if the inserted
row had a user-supplied value for that column. The assertion 
could then be triggered by the next statement.

The problem was only noticeable on debug builds of the server.

The cause of the problem was that the code for multi update did
not properly reset the TABLE->auto_increment_if_null flag after update.
The flag is used to indicate that a non-null value of an auto_increment field
has been provided by the user or retrieved from a current record.
Open_tables() contains an assertion that tests this flag, and this
was triggered in this case by ALTER TABLE.

This patch fixes the problem by resetting the auto_increment_if_null
field to FALSE once a row has been updated.

This bug is similar to Bug#47274, but for multi update rather
than INSERT DELAYED.

Test case added to update.test.

Knowledge of no SSL support is not used
Skip tests the same way e.g. innodb tests are
Does not refer to have_ssl_communication.inc, 
     will add this when merging to 6.0-codebase

Don't print entire log, but use extract_server_log() introduced by 46007

Test batches may be terminated too early
Avoid counting exp-fail tests

Use "#ifdef", not plain "#if".

Temporary tables may set join->group to 0 even though there is 
grouping. Also need to test if sum_func_count>0 when JOIN::exec() 
decides whether to present results in a grouped manner.

sql/sql_select.cc:
  Temporary tables may set join->group to 0 even though there is 
  grouping. Also need to test if sum_func_count>0 when JOIN::exec() 
  decides whether to present results in a grouped manner.

            columns without where/group
                     
Simple SELECT with implicit grouping used to return many rows if
the query was ordered by the aggregated column in the SELECT
list. This was incorrect because queries with implicit grouping
should only return a single record.
                              
The problem was that when JOIN:exec() decided if execution needed
to handle grouping, it was assumed that sum_func_count==0 meant
that there were no aggregate functions in the query. This
assumption was not correct in JOIN::exec() because the aggregate
functions might have been optimized away during JOIN::optimize().
                  
The reason why queries without ordering behaved correctly was
that sum_func_count is only recalculated if the optimizer chooses
to use temporary tables (which it does in the ordered case).
Hence, non-ordered queries were correctly treated as grouped.
                  
The fix for this bug was to remove the assumption that
sum_func_count==0 means that there is no need for grouping. This
was done by introducing variable "bool implicit_grouping" in the
JOIN object.

mysql-test/r/func_group.result:
  Add test for BUG#47280
mysql-test/t/func_group.test:
  Add test for BUG#47280
sql/opt_sum.cc:
  Improve comment for opt_sum_query()
sql/sql_class.h:
  Add comment for variables in TMP_TABLE_PARAM
sql/sql_select.cc:
  Introduce and use variable implicit_grouping instead of (!group_list && sum_func_count) in places that need to test if grouping is required. Also added comments for: optimization of aggregate fields for implicitly grouped queries  (JOIN::optimize) and choice of end_select method (JOIN::execute)
sql/sql_select.h:
  Add variable implicit_grouping, which will be TRUE for queries that contain aggregate functions but no GROUP BY clause. Also added comment to sort_and_group variable.

Difficult to debug due to lacking report
This does not solve the real issue, but extracts server log when it happens
Forst commit was incomplete, didn't cover all cases

      
The BINLOG statement was sharing too much code with the slave SQL thread, introduced with
the patch for Bug#32407. This caused statements to be logged with the wrong server_id, the
id stored inside the events of the BINLOG statement rather than the id of the running 
server.
      
Fix by rearranging code a bit so that only relevant parts of the code are executed by
the BINLOG statement, and the server_id of the server executing the statements will 
not be overrided by the server_id stored in the 'format description BINLOG statement'.

mysql-test/extra/binlog_tests/binlog.test:
  Added test to verify if the server_id stored in the 'format 
  description BINLOG statement' will override the server_id
  of the server executing the statements.
mysql-test/suite/binlog/r/binlog_row_binlog.result:
  Test result for bug#46640
mysql-test/suite/binlog/r/binlog_stm_binlog.result:
  Test result for bug#46640
sql/log_event.cc:
  Moved rows_event_stmt_clean() call from update_pos() to apply_event(). This in any case
  makes more sense, and is needed as update_pos() is no longer called when executing
  BINLOG statements.
  
  Moved setting of rli->relay_log.description_event_for_exec from 
  Format_description_log_event::do_update_pos() to 
  Format_description_log_event::do_apply_event()
sql/log_event_old.cc:
  Moved rows_event_stmt_clean() call from update_pos() to apply_event(). This in any case
  makes more sense, and is needed as update_pos() is no longer called when executing
  BINLOG statements.
sql/slave.cc:
  The skip flag is no longer needed, as the code path for BINLOG statement has been 
  cleaned up.
sql/sql_binlog.cc:
  Don't invoke the update_pos() code path for the BINLOG statement, as it contains code 
  that is redundant and/or harmful (especially setting thd->server_id).