[FIX] web: only abandon records on discard without savepoint

Revision on https://github.com/odoo/odoo/commit/9a9da5763b38a3bce54e9c4870af0032e38cacc3

The intent of the commit above was to no abandon records in a list on
discard when these records have been created from a `default_get`.

Also, the `default_get` may also perform an `onchange` that could create
more records. The records from this `onchange` must also be included in
the "do not abandon" rule.

However, the rule was too relax, so that any following `onchanges` from
a user interaction was also considered into this rule. As a result, it was
not possible to abandon such records.

With this fix, we restrict the rule to `default_get` (already the case) and
only the `onchange` right after a `default_get`. Any record created on an
`onchange` from a user interaction after a `default_get` should be abandoned
on discard.

Representation of creating the list:

                               savepoint
   |----------|-----------|-------||--------|------->
 create   default_get  onchange1         onchange2

record in the list is created by default_get or onchange1
    => do not abandon on discard
record in the list is created by onchange2
    => abandon on discard

1 files changed, 4 insertions, 2 deletions

diff --git a/addons/web/static/src/js/views/basic/basic_model.js b/addons/web/static/src/js/views/basic/basic_model.js
index 60c167ddfd1..36e9652dd9b 100644
--- a/addons/web/static/src/js/views/basic/basic_model.js
+++ b/addons/web/static/src/js/views/basic/basic_model.js
@@ -1542,8 +1542,10 @@ var BasicModel = AbstractModel.extend({
                             rec = self._makeDataPoint(params);
                             list._cache[rec.res_id] = rec.id;
                         }
-
-                        rec._noAbandon = true;
+                        // Do not abandon the record if it has been created
+                        // from `default_get`. The list has a savepoint only
+                        // after having fully executed `default_get`.
+                        rec._noAbandon = !list._savePoint;
                         list._changes.push({operation: 'ADD', id: rec.id});
                         if (command[0] === 1) {
                             list._changes.push({operation: 'UPDATE', id: rec.id});