BUG#28618 (Skipping into the middle of a group with SQL_SLAVE_SKIP_COUNTER

is possible):

When skipping the beginning of a transaction starting with BEGIN, the OPTION_BEGIN
flag was not set correctly, which caused the slave to not recognize that it was
inside a group. This patch sets the OPTION_BEGIN flag for BEGIN, COMMIT, ROLLBACK,
and XID events. It also adds checks if inside a group before decreasing the
slave skip counter to zero.

Begin_query_log_event was not marked that it could not end a group, which is now
corrected.

sql/slave.cc

@@ -1853,10 +1853,13 @@ static int exec_relay_log_event(THD* thd, Relay_log_info* rli)
       // EVENT_SKIP_NOT,
       "not skipped",
       // EVENT_SKIP_IGNORE,
-      "skipped because event originated from this server",
+      "skipped because event should be ignored",
       // EVENT_SKIP_COUNT
       "skipped because event skip counter was non-zero"
     };
+    DBUG_PRINT("info", ("OPTION_BEGIN: %d; IN_STMT: %d",
+                        thd->options & OPTION_BEGIN ? 1 : 0,
+                        rli->get_flag(Relay_log_info::IN_STMT)));
     DBUG_PRINT("skip_event", ("%s event was %s",
                               ev->get_type_str(), explain[reason]));
 #endif