Problem: In the mysqltest language, it was not possible to set the current
connection from a variable, and it was not possible to read the current
connection.
Fix: Allow setting the connection from a variable, like:
connection $variable;
and introduce the mysqltest language variable $CURRENT_CONNECTION, which
holds the name of the current connection.


client/mysqltest.cc:
  - Made select_connection use the common argument parser instead of its own
  home-rolled version. That allows variable expansion, for instance.
  - Made select_connection_name set the variable $CURRENT_CONNECTION, so that
  test scripts can use that.
  - Refactored a bit so that stuff that needs to be done when changing connection
  is located to one place.
mysql-test/t/mysqltest.test:
  Added test case for $CURRENT_CONNECTION and "connection $variable"

Problem 1: not_embedded_server runs SELECT FROM I_S.PROCESSLIST near the beginning.
check_testcase executes a query to the server before that. There is a race here,
because there is no guarantee that the thread executing check_testcase's query is
finished.
Problem 2: The SELECT FROM I_S.PROCESSLIST doens't seem very useful in the test.
It's at least misplaced.
Fix to both problems: Comment out SELECT FROM I_S.PROCESSLIST.


mysql-test/t/not_embedded_server.test:
  Commented out failing / useless test.

Problem: during a refactoring of mtr, a pattern for suppressing a warning from lowercase_table3 was lost.
Fix: re-introduce the suppression.
Problem 2: suppression was misspelt as supression. Fixed by adding a p.


mysql-test/include/mtr_warnings.sql:
  fixed spelling error
mysql-test/suite/rpl/t/rpl_bug33931.test:
  fixed spelling error
mysql-test/suite/rpl/t/rpl_idempotency.test:
  fixed spelling error
mysql-test/suite/rpl/t/rpl_temporary.test:
  fixed spelling error
mysql-test/suite/rpl/t/rpl_temporary_errors.test:
  fixed spelling error
mysql-test/t/lowercase_table3.test:
  fixed spelling error

Post-push fixes making it work on pushbuild's valgrind host, and clarifying the output.


mysql-test/lib/My/CoreDump.pm:
  - Improved parsing of mtr output so that it works on pushbuild's "valgrind" host.
  - Added stack trace for the thread that coredumped, to make output more readable when there are many threads.
  - Added explanation of what the output consists of.
  - Added early removal of temp file.

BUG#39008 Additional fix after review, remove files that could potentially be set to path outside datadir

BUG#38559 Annoying cygwin problem fixed by resolving  pid->winpid before kill instead of just after fork

mysql-test/suite/rpl/r/rpl_misc_functions.result:
  Using temporary table to avoid leaving a table after test.
mysql-test/suite/rpl/t/rpl_ps.test:
  Adding drop of table t1.

mysql-test/extra/rpl_tests/rpl_log.test:
  Removing extreneous start slave.
  Added missing drop of table t1.
mysql-test/suite/rpl/t/rpl_binlog_query_filter_rules.test:
  Replaced $MYSQLTEST_VARDIR/log with $MYSQLD_DATADIR
mysql-test/suite/rpl/t/rpl_misc_functions.test:
  Using temporary table instead to remove need for drop table.

WL4189 Add Handles.pm and use it from My::File::Path to show open handles. Rewrite rmtree to use File::Find so we can get better debug printouts when something fails

Disable the test case on valgrind. This is a backport to 5.1-rpl of
something that already exists in 5.1 main.


mysql-test/t/partition_not_windows.test:
  Disable the test case on valgrind platform.

Rotate event is automatically generated and written when rotating binary
log or relay log. Rotate events for relay logs are usually ignored by slave
SQL thread becuase they have the same server id as that of the slave.
However, if --replicate-same-server-id is enabled, rotate event
for relay log would be treated as if it's a rotate event from master, and
would be executed by slave to update the rli->group_master_log_name and
rli->group_master_log_pos to a wrong value and cause the MASTER_POS_WAIT
function to fail and return NULL.

This patch fixed this problem by setting a flag bit (LOG_EVENT_RELAY_LOG_F)
in the event to tell the SQL thread to ignore these Rotate events generated
for relay logs.

This patch also added another binlog event flag bit (LOG_EVENT_ARTIFICIAL_F)
to distinquish faked events, the method used before this was by checking if
log_pos was zero.


sql/log.h:
  Add a member to MYSQL_BIN_LOG to distinguish binary log from relay log.
sql/log_event.cc:
  Change artificial_event member to LOG_EVENT_ARTIFICIAL_F flag
  
  If LOG_EVENT_RELAY_LOG_F is set in the event flags for a rotate event, ignore it when updating position
  
  Refactored the code in Rotate_log_event::do_update_pos
sql/log_event.h:
  Add LOG_EVENT_RELAY_LOG_F flag to Log_event flags
  Add RELAY_LOG flag to Rotate_log_event flags
sql/sql_repl.cc:
  Set LOG_EVENT_ARTIFICIAL_F for fake rotate events

Memoize functions that converts between different paths, a given input string will always return the same output. This save a lot of calls to cygpath for example