lib: fix return value for n_m_reindex

Also update the documentation for the behaviour of n_m_get_thread_id
that this fix relies on.

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/notmuch.h b/lib/notmuch.h
index 82d6c10f..0dd442d4 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -1378,8 +1378,8 @@ notmuch_message_get_message_id (notmuch_message_t *message);
  * notmuch_message_destroy on 'message' or until a query from which it
  * derived is destroyed).
  *
- * This function will not return NULL since Notmuch ensures that every
- * message belongs to a single thread.
+ * This function will return NULL if triggers an unhandled Xapian
+ * exception.
  */
 const char *
 notmuch_message_get_thread_id (notmuch_message_t *message);