bpo-36522: Print all values for headers with multiple values. (GH-12681) (GH-12682)

(cherry picked from commit 461c416dd78a98f2bba7f323af8c9738e060b6f2)

Co-authored-by: Matt Houglum <houglum@google.com>
diff --git a/Lib/test/test_httplib.py b/Lib/test/test_httplib.py
index f816eac..4755f8b 100644
--- a/Lib/test/test_httplib.py
+++ b/Lib/test/test_httplib.py
@@ -348,7 +348,8 @@
         body = (
             b'HTTP/1.1 200 OK\r\n'
             b'First: val\r\n'
-            b'Second: val\r\n'
+            b'Second: val1\r\n'
+            b'Second: val2\r\n'
         )
         sock = FakeSocket(body)
         resp = client.HTTPResponse(sock, debuglevel=1)
@@ -357,7 +358,8 @@
         lines = output.getvalue().splitlines()
         self.assertEqual(lines[0], "reply: 'HTTP/1.1 200 OK\\r\\n'")
         self.assertEqual(lines[1], "header: First: val")
-        self.assertEqual(lines[2], "header: Second: val")
+        self.assertEqual(lines[2], "header: Second: val1")
+        self.assertEqual(lines[3], "header: Second: val2")
 
 
 class TransferEncodingTest(TestCase):