Problem: SP local variables that are used in ALTER EVENT
are not replicated properly.

Analysis: CALL statements are not written into binary log. Instead
each statement executed in SP is binlogged separately with the exception
that we modify query string: we replace uses of SP local variables with
NAME_CONST('spvar_name', <spvar-value>) calls. The code was written
under the assumption that this replacement was not required for at all
for all the queries in 'row' based format. But it can happen that DDLs
(which are always binlogged in statement mode irrespective of binlog
format) can also use SP local variables and they suffer due to the
above assumption. 'ALTER EVENT' in this bug case is one such cases

Fix: Any SP local variables used in a query should
be replaced with NAME_CONST(...) except for the case when it is DML
query and binlog format is 'ROW'.