This isn't a behavioral change---just a calrification in the documentation.
*
* This function performs a search and returns Xapian's best
* guess as to number of matching messages.
*
* 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);
*/
unsigned
notmuch_query_count_messages (notmuch_query_t *query);