patch 8.1.1286: running tests leaves XTest_tabpage_cmdheight file behind

Problem:    Running tests leaves XTest_tabpage_cmdheight file behind.
Solution:   Delete the right file. (closes #4350)
diff --git a/src/version.c b/src/version.c
index f4344aa..098c723 100644
--- a/src/version.c
+++ b/src/version.c
@@ -768,6 +768,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1286,
+/**/
     1285,
 /**/
     1284,