Do not try innodb_change_buffering_debug=2.

mysql-test/suite/sys_vars/r/innodb_change_buffering_debug_basic.result

@@ -55,9 +55,6 @@ Warnings:
 Warning	1292	Truncated incorrect innodb_change_buffering_debug value: '-2'
 set global innodb_change_buffering_debug=1e1;
 ERROR 42000: Incorrect argument type to variable 'innodb_change_buffering_debug'
-set global innodb_change_buffering_debug=2;
-Warnings:
-Warning	1292	Truncated incorrect innodb_change_buffering_debug value: '2'
 SET @@global.innodb_change_buffering_debug = @start_global_value;
 SELECT @@global.innodb_change_buffering_debug;
 @@global.innodb_change_buffering_debug

mysql-test/suite/sys_vars/t/innodb_change_buffering_debug_basic.test

@@ -42,7 +42,9 @@ set global innodb_change_buffering_debug='foo';
 set global innodb_change_buffering_debug=-2;
 --error ER_WRONG_TYPE_FOR_VAR
 set global innodb_change_buffering_debug=1e1;
-set global innodb_change_buffering_debug=2;
+# The value 2 is supposed to kill the server if there are unmerged changes.
+# Do not try to set the value to 2 or anything that can be clamped to 2.
+#set global innodb_change_buffering_debug=2;
 
 #
 # Cleanup