=== Problem ===

The test is dependent on binlog positions and checks
to see if the command 'START SLAVE' functions correctly
with the 'UNTIL' clause added to it. The 'UNTIL' clause
is added to specify that the slave should start and run
until the SQL thread reaches a given point in the master
binary log or in the slave relay log.

The test uses hard coded values for MASTER_LOG_POS and
RELAY_LOG_POS, instead of extracting it using
query_get_value() function. There is a test
'rpl.rpl_row_until' which does the similar thing but uses 
query_get_value() function to set the values of
MASTER_LOG_POS/ RELAY_LOG_POS. To be precise,
rpl.rpl_row_until is a modified version of
engines/func.rpl_row_until.test.

The use of hard coded values may lead the slave to stop at a position
which may differ from the expected position in the binlog file,
an example being the failure of engines/funcs.rpl_row_until in 
mysql-5.1 given as: 
"query 'select * from t2' failed. Table 'test.t2' doesn't exist".
In this case, the slave actually ran a couple of extra commands
as a result of which the slave first deleted the table and then
ran a select query on table, leading to the above mentioned failure.

=== Fix ===

1) Fixed the code for failure seen in rpl.rpl_row_until.
   This test was also failing although the symptoms of
   failure were different.
2) Copied the contents from rpl.rpl_row_until into
   into engines/funcs.rpl.rpl_row_until.
3) Updated engines/funcs.rpl_row_until.result accordingly.

mysql-test/suite/engines/funcs/r/rpl_row_until.result:
  modified to accomodate the changes in corresponding
  test file.
mysql-test/suite/engines/funcs/t/disabled.def:
  removed from the list of disabled tests.
mysql-test/suite/engines/funcs/t/rpl_row_until.test:
  fixed rpl.rpl_row_until and copied its content to
  engines/funcs.rpl_row_until. The reason being both
  are same tests but rpl.rpl_row_until is an
  updated version.
mysql-test/suite/rpl/t/disabled.def:
  removed from the list of disabled tests.
sql/sql_repl.cc:
  Added a check to catch an improper combination
  of arguements passed to 'START SLAVE UNTIL'. Earlier,
  START SLAVE UNTIL MASTER_LOG_FILE='master-bin.000001',
  MASTER_LOG_POS=561, RELAY_LOG_POS=12;
  passed. It is now detected and an error is reported.