patch 9.0.1667: regression test doesn't fail when fix is reverted

Problem:    Regression test doesn't fail when fix is reverted.
Solution:   Add "n" to 'cpoptions' instead of using :winsize. (closes #12587,
            issue #12528)
diff --git a/src/version.c b/src/version.c
index 948a948..5c83d40 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1667,
+/**/
     1666,
 /**/
     1665,