Bug #4601 Views: A view based on a view is not updatable

Description:
If one creates a view (e.g. vt1) based on a single underlying table (e.g. t1), then creates another view (vt2) based upon the first view, the second view is not updatable even though it follows the rule that a view based upon a single underlying table should be updatable. At UPDATE, MySQL returns this error:
ERROR 1288 (HY000): The target table vt2 of the UPDATE is not updatable

How to repeat:
create table t1 (col1 int,col2 char(22));
insert into t1 values(5,'Hello, world of views');
create view vt1 as select * from t1;
create view vt2 as select * from vt1;
update vt2 set col2='Hello, view world';

ChangeSet 
  1.1726 04/07/22 17:52:04 bell@sanja.is.com.ua +5 -0 
  made different fields for view updatebility in principle and updatability during this 
execution (BUG#4601)

Thank you for bug report! bugfix is pushed in our source repository.