patch 7.4.1547
Problem:    Getting a cterm highlight attribute that is not set results in the
            string "-1".
Solution:   Return an empty string. (Taro Muraoka)
diff --git a/src/version.c b/src/version.c
index fc9cebe..c2ba553 100644
--- a/src/version.c
+++ b/src/version.c
@@ -744,6 +744,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1547,
+/**/
     1546,
 /**/
     1545,