[libpng16] Bump version to 1.6.13beta01
diff --git a/pngset.c b/pngset.c
index 0c827d3..cde4c6d 100644
--- a/pngset.c
+++ b/pngset.c
@@ -1,7 +1,7 @@
 
 /* pngset.c - storage of image information into info struct
  *
- * Last changed in libpng 1.6.11 [June 12, 2014]
+ * Last changed in libpng 1.6.11 [June 5, 2014]
  * Copyright (c) 1998-2014 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)