patch 8.1.1660: assert_fails() does not fail inside try/catch

Problem:    Assert_fails() does not fail inside try/catch.
Solution:   Set trylevel to zero. (Ozaki Kiichi, closes #4639)
diff --git a/src/version.c b/src/version.c
index 5e83159..6af9aba 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1660,
+/**/
     1659,
 /**/
     1658,