+Indicate to the user if two files with the same message ID have
+content that is actually different in some interesting way. Perhaps
+notmuch initially sees all changes as interesting, and quickly learns
+from the user which changes are not interesting (such as the very
+common mailing-list footer).
+
+Fix notmuch_query_count_messages to share code with
+notmuch_query_search_messages rather than duplicating code. (And
+consider renaming it as well.)
+