[FIX] web: click on many2many tag with no color

Before this rev., a traceback was raised when the user clicked on a
many2many tag in a kanban view without color field.

For instance, it was the case in the kanban view opened by clicking
on the Lead/Opportunity section of the activities icon in the
systray.

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

@@ -1678,6 +1678,7 @@ var KanbanFieldMany2ManyTags = FieldMany2ManyTags.extend({
         _.each(this.value.data, function (m2m) {
             var $tag = $('<span>')
                     .text(m2m.data.display_name)
+                    .data('res_id', m2m.res_id)
                     .prepend('<span>')
                     .appendTo(self.$el);
             if (self.colorField in m2m.data) {
@@ -1686,7 +1687,6 @@ var KanbanFieldMany2ManyTags = FieldMany2ManyTags.extend({
                     $tag.hide();
                 } else {
                     $tag.addClass('o_tag o_tag_color_' + m2m.data[self.colorField]);
-                    $tag.data('res_id', m2m.res_id);
                 }
             } else {
                 // display tags in grey by default

addons/web/static/tests/views/kanban_tests.js

@@ -564,6 +564,43 @@ QUnit.module('Views', {
         kanban.destroy();
     });
 
+    QUnit.test('many2many_tags with no color field and search by tag', function (assert) {
+        assert.expect(3);
+
+        delete this.data.category.fields.color;
+        this.data.partner.records[0].category_ids = [6, 7];
+
+        var kanban = createView({
+            View: KanbanView,
+            model: 'partner',
+            data: this.data,
+            arch: '<kanban><templates><t t-name="kanban-box">' +
+                    '<div>' +
+                        '<field name="category_ids" widget="many2many_tags"/>' +
+                        '<field name="foo"/>' +
+                    '</div>' +
+                '</t></templates></kanban>',
+            intercepts: {
+                add_filter: function (event) {
+                    assert.deepEqual(event.data, {
+                        domain: "[['category_ids','=','gold']]",
+                        help: 'gold',
+                    }, "should trigger an 'add_filter' event with correct data");
+                },
+            },
+        });
+
+        var $first_record = kanban.$('.o_kanban_record:first()');
+        assert.strictEqual($first_record.find('.o_field_many2manytags .o_tag').length, 2,
+            'first record should contain 2 tags');
+        assert.ok($first_record.find('.o_tag.o_tag_color_0').hasClass('o_tag_color_0'),
+            'both tags should have the default color');
+        // click on a tag to trigger a search by tag
+        kanban.$('.o_tag:contains(gold):first').click();
+
+        kanban.destroy();
+    });
+
     QUnit.test('can drag and drop a record from one column to the next', function (assert) {
         assert.expect(9);