patch 8.2.1538: Python: iteration over vim objects fails to keep reference

Problem:    Python: iteration over vim objects fails to keep reference.
Solution:   Keep a reference for the object. (Paul Ollis, closes #6803,
            closes #6806)
diff --git a/src/version.c b/src/version.c
index d4d525b..9e3430a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1538,
+/**/
     1537,
 /**/
     1536,