This patch adds for "--ps-protocol" second execution
of queries "SELECT".
Also in this patch it is added ability to disable/enable
(--disable_ps2_protocol/--enable_ps2_protocol) second
execution for "--ps-prototocol" in testcases.
The problem was that the code in replication didn't distinguish between a
setval() failing because the stored sequence number was bigger than the
current (should have been ignored) and a failure from the storage engine.
