patch 8.2.0644: insufficient testing for invalid function arguments

Problem:    Insufficient testing for invalid function arguments.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #5988)
diff --git a/src/version.c b/src/version.c
index e78fc73..8c4cc71 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    644,
+/**/
     643,
 /**/
     642,