SF patch 1631942 by Collin Winter:
(a) "except E, V" -> "except E as V"
(b) V is now limited to a simple name (local variable)
(c) V is now deleted at the end of the except block
diff --git a/Doc/tools/mkhowto b/Doc/tools/mkhowto
index 21cd6fb..02a215d 100755
--- a/Doc/tools/mkhowto
+++ b/Doc/tools/mkhowto
@@ -599,7 +599,7 @@
     options = Options()
     try:
         args = options.parse(sys.argv[1:])
-    except getopt.error, msg:
+    except getopt.error as msg:
         error(options, msg)
     if not args:
         # attempt to locate single .tex file in current directory: