[FIX] core: ignore id field in o2ms

Followup to odoo/odoo#43117 (backporting from something which breaks
in 12.3): if the o2m somehow has an id field, this field should be
ignored when extracting values to save, for the purpose of both
actually saving and extracting values for e.g. default_get.

closes odoo/odoo#43204

Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>

odoo/tests/common.py

@@ -1488,7 +1488,7 @@ class Form(object):
                         context['•parent•'] = self._values
                         vs = {
                             k: v for k, v in items
-                            if all_fields or nodes[k].get('force_save') or not self._get_modifier(k, 'readonly', modmap=modifiers, vals=context)
+                            if (all_fields and k != 'id') or nodes[k].get('force_save') or not self._get_modifier(k, 'readonly', modmap=modifiers, vals=context)
                         }
                     v.append((c, rid, vs))