patch 8.1.0277: 'incsearch' highlighting wrong in a few cases

Problem:    'incsearch' highlighting wrong in a few cases.
Solution:   Fix using last search pattern.  Restore highlighting when changing
            command. (issue #3321)
diff --git a/src/version.c b/src/version.c
index 98b2335..a3f81f0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -795,6 +795,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    277,
+/**/
     276,
 /**/
     275,