The bug was fixed by MDEV-22599 bugfix, which changed `Field::cmp` call
to `Field::cmp_prefix` in `TABLE::check_period_overlaps`.

The trick is that `Field_bit::cmp` apparently calls `Field_bit::cmp_key`,
which condiders an argument an actual pointer to data, which isn't correct
for `Field_bit`, since it stores data by `bit_ptr`. which is in the
beginning of the record, and using `ptr` is incorrect (we use it through
`ptr_in_record` call)