1 files changed, 19 insertions, 0 deletions
diff --git a/Mailman/Message.py b/Mailman/Message.py
index 5d68e7ef..20610dc7 100644
--- a/Mailman/Message.py
+++ b/Mailman/Message.py
@@ -59,6 +59,25 @@ class Generator(email.Generator.Generator):
         return self.__class__(fp, self._mangle_from_,
                 self.__children_maxheaderlen, self.__children_maxheaderlen)
 
+    # This is the _handle_message method with the fix for bug 7970.
+    def _handle_message(self, msg):
+        s = StringIO()
+        g = self.clone(s)
+        # The payload of a message/rfc822 part should be a multipart sequence
+        # of length 1.  The zeroth element of the list should be the Message
+        # object for the subpart.  Extract that object, stringify it, and
+        # write it out.
+        # Except, it turns out, when it's a string instead, which happens when
+        # and only when HeaderParser is used on a message of mime type
+        # message/rfc822.  Such messages are generated by, for example,
+        # Groupwise when forwarding unadorned messages.  (Issue 7970.)  So
+        # in that case we just emit the string body.
+        payload = msg.get_payload()
+        if isinstance(payload, list):
+            g.flatten(msg.get_payload(0), unixfrom=False)
+            payload = s.getvalue()
+        self._fp.write(payload)
+
 
 
 class Message(email.Message.Message):