Actually, this thing is more complex to solve than I thought.
Specifically, as described in
http://www.opengroup.org/onlinepubs/007908775/xsh/stdarg.h.html stdarg
requires that variable argument functions have at least one fixed argument.
This is implied by the declaration of "void va_start(va_list ap, argN);".
As explained in the original ticket description, and also described
before in the above link, va_start() must be called before any call to
va_arg(), and this includes any access to the argument list using
__va_copy namely.

The problem is that at least objargs_mktuple(), line 2649 of
Objects/abstract.c does not have a first fixed argument.