* debug.cc (add_handle): Issue warning on attempts to add the same handle more

than once.
* fhandler_tty.cc (fhandler_tty_slave::open): Protect some handles.
(fhandler_tty_common::close): Use proper name when closing handles.
(fhandler_pty_master::close): Don't close to_slave or from_slave since they've
already been closed earlier in the function.
* sigproc.cc (proc_subproc): Don't protect vchild->hProcess.  Expect that the
caller will do this, instead.
* tty.cc (tty_list::terminate): Use proper name when closing handles.
(tty::make_pipes): Protect some handles.

winsup/cygwin/debug.cc

@@ -246,8 +246,14 @@ add_handle (const char *func, int ln, HANDLE h, const char *name)
   handle_list *hl;
   lock_debug ();
 
-  if (find_handle (h))
-    goto out;		/* Already did this once */
+  if ((hl = find_handle (h)))
+    {
+      system_printf ("%s:%d - multiple attempts to add handle %s<%p>", func,
+		     ln, name, h);
+      system_printf (" previously allocated by %s:%d(%s<%p>)",
+		     hl->func, hl->ln, hl->name, hl->h);
+      goto out;		/* Already did this once */
+    }
 
   if ((hl = newh()) == NULL)
     {