Patch for issue 2848, mostly by Humberto Diogenes, with a couple of
small fixes by Barry.  This removes mimetools from the stdlib.
diff --git a/Demo/scripts/mboxconvert.py b/Demo/scripts/mboxconvert.py
index 787c760..2e44f06 100755
--- a/Demo/scripts/mboxconvert.py
+++ b/Demo/scripts/mboxconvert.py
@@ -89,7 +89,7 @@
         t = time.mktime(tt)
     else:
         sys.stderr.write(
-                'Unparseable date: %r\n' % (m.getheader('Date'),))
+                'Unparseable date: %r\n' % (m.get('Date'),))
         t = os.fstat(f.fileno())[stat.ST_MTIME]
     print('From', email, time.ctime(t))
     # Copy RFC822 header