test: strengthen #58 dedup trap to assert filtering

The trap mocked issue.filter to return only issue 2, so result == [2]
would pass even with a wrong fix that suppresses TypeError but keeps all
entries. Now the API mock returns both issues; only correct filtering
of the pre-cutoff time entry keeps the result at [2].

Refs #67, #58

tests/test_client.py

@@ -779,12 +779,21 @@ def test_dedup_normalizes_naive_created_on_to_utc(mock_redmine_class):
 
     mock_redmine.time_entry.filter.return_value = [e_old, e_new]
 
+    mock_issue1 = mock.MagicMock()
+    mock_issue1.id = 1
+    mock_issue1.project = "P"
+    mock_issue1.subject = "T"
+    mock_issue1.status = "New"
     mock_issue2 = mock.MagicMock()
     mock_issue2.id = 2
     mock_issue2.project = "P"
     mock_issue2.subject = "T"
     mock_issue2.status = "New"
-    mock_redmine.issue.filter.return_value = [mock_issue2]
+    # API возвращает обе задачи: issue 1 попадёт в результат, только если
+    # её time entry не отсечён дедупликацией. Корректный фикс #58 отсекает
+    # e_old (created_on/updated_on < cutoff) -> [2]; неправильный фикс
+    # "погасить TypeError и оставить всё" даст [1, 2] и тест упадёт.
+    mock_redmine.issue.filter.return_value = [mock_issue1, mock_issue2]
 
     result = fetch_issues_with_spent_time(
         "2026-07-01", "2026-07-01", dedup_before=dedup_cutoff