updated for version 7.4.591
Problem:    test_listlbr_utf8 fails when the conceal feature is not available.
Solution:   Check for the conceal feature. (Kazunobu Kuriyama)
diff --git a/src/version.c b/src/version.c
index bef9b19..33f8a97 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    591,
+/**/
     590,
 /**/
     589,