Problem: When RAND() is binlogged in statement mode, the seed is
binlogged too, so the replication slave generates the same
sequence of random numbers. This makes replication work in many
cases, but not in all cases: the order of rows is not guaranteed
for, e.g., UPDATE or INSERT...SELECT statements, so the row data
will be different if master and slave retrieve the rows in
different orders.
Fix: Mark RAND() as unsafe. It will generate a warning if
binlog_format=STATEMENT and switch to row-logging if
binlog_format=ROW.