The editable list has a `is_valid` method which checks that all the
records it contains have valid data. The problem is that it was
considering that all the records in the `dataset.cache` were part of
the x2x field the editable list is working with. This is wrong as the
`dataset.cache` can contain information which are not part of the
editable list anymore.
See the commit which introduced the use of the `dataset.cache`:
a9d20d9fa0
This was causing issues with rare cases of an editable list which
contains another editable list (even invisible) which was sharing
common information with its parent editable list.
opw-710627
qsm-odoo
3aabf8101a