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/Tools/scripts/linktree.py b/Tools/scripts/linktree.py
index 995f2ef..7f17046 100755
--- a/Tools/scripts/linktree.py
+++ b/Tools/scripts/linktree.py
@@ -32,13 +32,13 @@
         return 1
     try:
         os.mkdir(newtree, 0777)
-    except os.error, msg:
+    except os.error as msg:
         print newtree + ': cannot mkdir:', msg
         return 1
     linkname = os.path.join(newtree, link)
     try:
         os.symlink(os.path.join(os.pardir, oldtree), linkname)
-    except os.error, msg:
+    except os.error as msg:
         if not link_may_fail:
             print linkname + ': cannot symlink:', msg
             return 1
@@ -51,7 +51,7 @@
     if debug: print 'linknames', (old, new, link)
     try:
         names = os.listdir(old)
-    except os.error, msg:
+    except os.error as msg:
         print old + ': warning: cannot listdir:', msg
         return
     for name in names: