[dl:http] support 'metadata-http' option name (gh#7661)

test/test_downloader.py

@@ -166,6 +166,16 @@ class TestDownloaderConfig(unittest.TestCase):
         self.assertEqual(dl.rate(), 42)
         self.assertEqual(dl.part, False)
 
+    def test_config_http_metadata(self):
+        for key in ("metadata-http", "http-metadata"):
+            config.clear()
+            config.set((), key, "gdl_http")
+
+            job = FakeJob()
+            dl = downloader.find("http")(job)
+
+            self.assertEqual(dl.metadata, "gdl_http", key)
+
 
 class TestDownloaderBase(unittest.TestCase):