Alter online table x (no options) possible

This no-op of an operations should be able to occur without locks and
occur online.

mysql-test/r/alter_table_online.result

@@ -11,6 +11,7 @@ alter online table t1 comment "new comment";
 ERROR 0A000: LOCK=NONE/SHARED is not supported for this operation. Try LOCK=EXCLUSIVE.
 alter online table t1 rename to t2;
 ERROR 0A000: LOCK=NONE/SHARED is not supported for this operation. Try LOCK=EXCLUSIVE.
+alter online table t1 algorithm=INPLACE, lock=NONE;
 drop table t1;
 create temporary table t1 (a int not null primary key, b int, c varchar(80), e enum('a','b'));
 insert into t1 (a) values (1),(2),(3);

mysql-test/t/alter_table_online.test

@@ -7,7 +7,7 @@
 drop table if exists t1,t2,t3;
 --enable_warnings
 #
-# Test of things that can be done online
+# Test of things that can not be done online
 #
 
 create table t1 (a int not null primary key, b int, c varchar(80), e enum('a','b'));
@@ -24,6 +24,10 @@ alter online table t1 comment "new comment";
 --error ER_ALTER_OPERATION_NOT_SUPPORTED
 alter online table t1 rename to t2;
 
+# No OPs
+
+alter online table t1 algorithm=INPLACE, lock=NONE;
+
 drop table t1;
 
 #

sql/sql_table.cc

@@ -8431,6 +8431,7 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
   THD_STAGE_INFO(thd, stage_setup);
   if (!(alter_info->flags & ~(Alter_info::ALTER_RENAME |
                               Alter_info::ALTER_KEYS_ONOFF)) &&
+      alter_info->flags != 0 &&
       alter_info->requested_algorithm !=
       Alter_info::ALTER_TABLE_ALGORITHM_COPY &&
       !table->s->tmp_table) // no need to touch frm
@@ -8449,7 +8450,8 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
     DBUG_RETURN(res);
   }
 
-  handle_if_exists_options(thd, table, alter_info);
+  if (alter_info->flags != 0)
+    handle_if_exists_options(thd, table, alter_info);
 
   /*
     Look if we have to do anything at all.