to the client only after the binlog write and engine commit.
No testcase for this bug, as to reproduce it, we need to "kill -9" mysqld,
which we cannot do in the testsuite. But, I tested by hand.


sql/sql_load.cc:
  D in ACID means that once the client got the ok from the server, the data
  is durable on disk. Implies that the ok must be sent after the binlog write
  and after the engine commit, not before.