lib: Document that notmuch_query_count_messages may return 0 if an exception occurs

This isn't a behavioral change---just a calrification in the documentation.

diff --git a/lib/notmuch.h b/lib/notmuch.h
index 921b0fcfa519ee3f4eb54827ad1ac92d64a4c8c4..54616336eabc7e2ac8dede6335e738e81b56d6ed 100644 (file)
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -506,6 +506,9 @@ notmuch_threads_destroy (notmuch_threads_t *threads);
  *
  * This function performs a search and returns Xapian's best
  * guess as to number of matching messages.
+ *
+ * If a Xapian exception occurs, this function may return 0 (after
+ * printing a message).
  */
 unsigned
 notmuch_query_count_messages (notmuch_query_t *query);