[FIX] web: clear input on clicking 'Create and Edit' from many2one fields

We clear the input field when clicking 'Create and Edit' to ensure that
the field is empty if the user chooses to cancel the record creation. If
a record is indeed created, then the field value will still be updated.

addons/web/static/src/js/fields/relational_fields.js

@@ -371,9 +371,14 @@ var FieldMany2One = AbstractField.extend({
                 }
                 // create and edit ...
                 if (create_enabled && !self.nodeOptions.no_create_edit) {
+                    var createAndEditAction = function () {
+                        // Clear the value in case the user clicks on discard
+                        self.$('input').val('');
+                        return self._searchCreatePopup("form", false, self._createContext(search_val));
+                    };
                     values.push({
                         label: _t("Create and Edit..."),
-                        action: self._searchCreatePopup.bind(self, "form", false, self._createContext(search_val)),
+                        action: createAndEditAction,
                         classname: 'o_m2o_dropdown_option',
                     });
                 } else if (values.length === 0) {

addons/web/static/tests/fields/relational_fields_tests.js

@@ -1489,7 +1489,7 @@ QUnit.module('relational_fields', {
 
     QUnit.test('pressing ENTER on a \'no_quick_create\' many2one should not trigger M2ODialog', function (assert) {
         var done = assert.async();
-        assert.expect(1);
+        assert.expect(2);
 
         var M2O_DELAY = relationalFields.FieldMany2One.prototype.AUTOCOMPLETE_DELAY;
         relationalFields.FieldMany2One.prototype.AUTOCOMPLETE_DELAY = 0;
@@ -1527,6 +1527,10 @@ QUnit.module('relational_fields', {
                 $input.blur();
                 assert.strictEqual($('.modal').length, 1,
                     "should have one modal in body");
+                // Check that discarding clears $input
+                $('.modal .o_form_button_cancel').click();
+                assert.strictEqual($input.val(), '',
+                    "the field should be empty");
                 form.destroy();
                 relationalFields.FieldMany2One.prototype.AUTOCOMPLETE_DELAY = M2O_DELAY;
                 done();