fix manual parser refresh reliability

tests/apps/parsers/test_gisp_client.py

@@ -49,6 +49,35 @@ class GispProductsClientTest(SimpleTestCase):
         ):
             GispProductsClient(max_records=10_001)
 
+    def test_retries_transient_server_error(self):
+        calls = 0
+
+        def handle_page(_request, _body: bytes) -> Response:
+            nonlocal calls
+            calls += 1
+            if calls == 1:
+                return Response(status=504, body=b"gateway timeout")
+            return Response(
+                body=b'{"ok":true,"total_count":1,"items":[]}',
+                headers={"Content-Type": "application/json"},
+            )
+
+        with HTTPTestServer() as server:
+            server.add_route("POST", "/pp719v2/pub/prod/b/", handle_page)
+            client = GispProductsClient(
+                base_url=server.base_url,
+                max_pages=1,
+                retry_backoff_seconds=0,
+                http_adapter=server.adapter,
+            )
+            with self.assertRaisesMessage(
+                GispProductsClientError,
+                "empty page before total_count",
+            ):
+                client.fetch_products()
+
+        self.assertEqual(calls, 2)
+
     def test_fetch_products_follows_skip_pagination_and_maps_items(self):
         requests: list[dict] = []