patch 8.0.0559: setting ttytype to xxx does not always fail

Problem:    Setting ttytype to xxx does not always fail as expected. (Marvin
            Schmidt)
Solution:   Catch both possible errors. (closes #1601)
diff --git a/src/version.c b/src/version.c
index 26df634..e73e1fa 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    559,
+/**/
     558,
 /**/
     557,