_structure(): Don't get the whole Content-Type: header, just get the
type with get_type().
diff --git a/Lib/email/Iterators.py b/Lib/email/Iterators.py
index 5253710..0d0e0b2 100644
--- a/Lib/email/Iterators.py
+++ b/Lib/email/Iterators.py
@@ -15,7 +15,7 @@
 def _structure(msg, level=0):
     """A handy debugging aid"""
     tab = ' ' * (level * 4)
-    print tab + msg.get('content-type', msg.get_default_type())
+    print tab + msg.get_type(msg.get_default_type())
     if msg.is_multipart():
         for subpart in msg.get_payload():
             _structure(subpart, level+1)