Behavior of MariaDB 10.3.11 batch update processing changed from non-atomic insert to atomic insert

When we switched from MariaDB 10.1.16 server to Mariadb 10.3.11, the behavior of MariaDB batch update processing changed from non-atomic insert to atomic insert. This is an upward compatibility issue for us.
In the repro2 I attached, we attempt to insert a block of 3 rows, one of which has a duplicate primary key value.
With MaraiaDB server 10.1.16, the non-duplicate rows of a block insert would be inserted up to the first error. With MariaDB server 10.3.11, no rows are inserted and we don't know which row of the block caused the error, so we cannot attempt to insert all non-error rows. This looks like a bug. Is there a setting to restore the original behavior?