MDEV-21147 Assertion `marked_for_read()' upon UPDATE on versioned table via view

Unit prepare prematurely fixed field which must be fixed via
setup_conds() to correctly update table->covering_keys.

Call vers_setup_conds() directly instead, because actually everything
else is not needed.

mysql-test/suite/versioning/r/update.result

@@ -295,5 +295,9 @@ primary key (pk)
 create or replace view v1 as select * from t1;
 insert into t1 values  (1, null, 'd') ,  (2, null, 'i') ;
 update v1 set a= null where b = '';
+create or replace table t1 (id int, k int, primary key (id)) engine=innodb with system versioning;
+insert into t1 values (1,1),(2,2);
+create or replace view v1 as select * from t1;
+update v1 set id= 2 where k = 0;
 drop view v1;
 drop table t1;

mysql-test/suite/versioning/t/update.test

@@ -214,6 +214,11 @@ create or replace view v1 as select * from t1;
 insert into t1 values  (1, null, 'd') ,  (2, null, 'i') ;
 update v1 set a= null where b = '';
 
+create or replace table t1 (id int, k int, primary key (id)) engine=innodb with system versioning;
+insert into t1 values (1,1),(2,2);
+create or replace view v1 as select * from t1;
+update v1 set id= 2 where k = 0;
+
 # cleanup
 drop view v1;
 drop table t1;

sql/sql_derived.cc

@@ -707,8 +707,9 @@ bool mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *derived)
       case SQLCOM_DELETE_MULTI:
       case SQLCOM_UPDATE:
       case SQLCOM_UPDATE_MULTI:
-        if ((res= unit->prepare(derived, derived->derived_result, 0)))
+        if ((res= unit->first_select()->vers_setup_conds(thd, derived->merge_underlying_list)))
           goto exit;
+        derived->where= and_items(thd, derived->where, derived->merge_underlying_list->where);
       default:
         break;
       }