Foreign key update fails with "unicode_ci"

[pgulutzan]

I have Ubuntu 18.04. I have Tarantool 2.0, pulled from source today.

I execute these statements:
drop table t6;
drop table t5;
create table t5 (s1 char(5) collate "unicode_ci"primary key);
create table t6 (s1 int primary key, s2 char(5) collate "unicode_ci" references t5 (s1));
insert into t5 values ('a');
insert into t6 values (1,'a');
update t5 set s1 = 'A';

I get "Error . FOREIGN KEY constraint failed".