#12515: email now registers a defect if the MIME end boundary is missing.

This commit also restores the news item for 167256 that it looks like
Terry inadvertently deleted.  (Either that, or I don't understand
now merging works...which is equally possible.)

Lib/email/errors.py

@@ -42,6 +42,9 @@ class NoBoundaryInMultipartDefect(MessageDefect):
 class StartBoundaryNotFoundDefect(MessageDefect):
     """The claimed start boundary was never found."""
 
+class CloseBoundaryNotFoundDefect(MessageDefect):
+    """A start boundary was found, but not the corresponding close boundary."""
+
 class FirstHeaderLineIsContinuationDefect(MessageDefect):
     """A message had a continuation line as its first header line."""