Add a test for get_all() returning failobj.  msg_20.txt is a sample
message with multiple CC: fields, used in the get_all() test.
diff --git a/Lib/test/test_email.py b/Lib/test/test_email.py
index 0a6b808..06aae2b 100644
--- a/Lib/test/test_email.py
+++ b/Lib/test/test_email.py
@@ -50,6 +50,12 @@
 
 # Test various aspects of the Message class's API
 class TestMessageAPI(TestEmailBase):
+    def test_get_all(self):
+        eq = self.assertEqual
+        msg = self._msgobj('msg_20.txt')
+        eq(msg.get_all('cc'), ['ccc@zzz.org', 'ddd@zzz.org', 'eee@zzz.org'])
+        eq(msg.get_all('xx', 'n/a'), 'n/a')
+
     def test_get_charsets(self):
         eq = self.assertEqual