the test was doing
--replace_result $con_id con_id
eval SHOW EXPLAIN FOR $con_id;
with the intention of replacing the variable part of the statement
in the result log. But actually replace_result replaces everything
that matches. In particular, when $con_id is 100, the warning
Note 1003 select sleep(100000)
becomes
Note con_id3 select sleep(con_id000)