Version for 4.0. Committed for merge.
If the result table is one of the select tables in INSERT SELECT,
we must not disable the result tables indexes before selecting.
mysql_execute_command() detects the match for other reasons and
adds the flag OPTION_BUFFER_RESULT to the 'select_options'.
In this case the result is put into a temporary table first.
Hence, we can defer the preparation of the insert
table until the result is to be used.
insertion of new records partially failed. It would get logged because of the
logic to log a partially-failed 'INSERT ... SELECT' (which can't be rolled back
in non-transactional tables), but 'CREATE TABLE ... SELECT' is always rolled
back on failure, even for non-transactional tables. (Bug #6682)
(Original fix reimplemented after review by Serg and Guilhem.)
