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/prechm.py b/Doc/tools/prechm.py
index 57a43fd..db1f965 100644
--- a/Doc/tools/prechm.py
+++ b/Doc/tools/prechm.py
@@ -448,7 +448,7 @@
 def openfile(file):
     try:
         p = open(file, "w")
-    except IOError, msg:
+    except IOError as msg:
         print file, ":", msg
         sys.exit(1)
     return p
@@ -466,7 +466,7 @@
 
     try:
         optlist, args = getopt.getopt(args, 'ckpv:')
-    except getopt.error, msg:
+    except getopt.error as msg:
         print msg
         usage()