Third updated patch - this version also includes copyright notice in added Perl script.
This patch implements a check for such modules at runtime. If modules are not found or unable to load, the test is skipped with 
the following message:
            
            [ skipped ]  Test needs Perl modules DBI and DBD::mysql
            
Checks are done via a helper Perl script which looks for the module in a runtime environment that is as similar to that of the 
mysqlhotcopy script as possible (thus not intended for Windows environments at this time).
The helper script tells mysql-test about the result by writing information to a temporary file that is later read by mysql-test.
See comments in added files (have_dbi_dbd-mysql.inc and checkDBI_DBD-mysql.pl) for details.
The patch also removes the mysqlhotcopy tests from the list of disabled tests.

for external_size
      
rb://581 approved by Marko

trx_get_trx_by_xid(): Invalidate trx->xid after a successful lookup,
so that subsequent callers will not find the same transaction.

The only callers of trx_get_trx_by_xid() will be invoking
innobase_commit_low() or innobase_rollback_trx(), and those code paths
should not depend on trx->xid.

rb://584 approved by Jimmy Yang

Fix backported from to 5.0.
"Remove the alignment option, let valgrind use its default"

Updated the copyright.

due to potentially uninitialized variable

row_upd_changes_ord_field_binary(): Initialize dfield_len to suppress the
warning. The compiler cannot know that row_ext_lookup() does initialize
dfield_len for us, as it is defined in a different module.

mlog_parse_string(): Enclose the comparison in UNIV_UNLIKELY,
not the comparand.

row_vers_build_for_semi_consistent_read(): Dereference version_trx before
releasing kernel_mutex, but not thereafter.

buf_block_alloc(): ulint zip_size is always 0.
buf_LRU_get_free_block(): ulint zip_size is always 0.
buf_LRU_free_block(): ibool* buf_pool_mutex_released is always NULL.

Remove these parameters.

buf_LRU_get_free_block(): Simplify the initialization of block->page.zip
and release buf_pool_mutex() earlier.

Updated Copyright.

Race condition may occur: mtr sees the .expect file but it's empty
Fix: wait and try again if file is empty
Addendum: try again if line isn't 'wait' or 'restart'
Also added verbose printout of extra restart options

ZERO
      
When dates are represented internally as strings, i.e. when a string constant
is compared to a date value, both values are converted to long integers,
ostensibly for fast comparisons. DATE typed integer values are converted to
DATETIME by multiplying by 1,000,000 (each digit pair representing hour,
minute and second, respectively). But the mechanism did not distuinguish
cached INTEGER values, already in correct format, from newly converted
strings.

Fixed by marking the INTEGER cache as being of DATETIME format.

The test were using external tools not available for embedded.

Fixed by rewriting the test to not rely on external tools like the mysql-client

Also fixed some non portable --exec commands and replaced #p# to #P# to pass
on windows.

            
rpl_packet got a timeout failure sporadically on PB when stopping
slave. The real reason of this bug is that STOP SLAVE stopped
IO thread first and then stopped SQL thread. It was
possible that IO thread stopped after replicating part of a
transaction which SQL thread was executing. SQL thread would
be hung if the transaction could not be rolled back safely.
            
After this patch, STOP SLAVE will stop SQL thread first and then stop IO
thread, which guarantees that IO thread will fetch the reset of the
events of the transaction that SQL thread is executing, so that SQL
thread can finish the transaction if it cannot be rolled back safely.
            
Added below auxiliary files to make the test code neater.
restart_slave_sql.inc
rpl_connection_master.inc
rpl_connection_slave.inc
rpl_connection_slave1.inc

Undoing the patch, it complicates the code but is not the solution

I do not beleive newline mismatch could be the cause of this failure
First, I cannot see how this could be a problem, mtr ignores the newline
  when reading the expect file, and the file is written and read on Windows.
Second, if this really was the problem it should have been deterministic:
  either the newline is correctly interepreted or it is not.

rw_lock_debug_print(): Add parameter FILE* for specifying the output stream.
rw_lock_list_print_info(): Invoke rw_lock_debug_print() on file, not stderr.