Duplication warning when using (lisp ...)

[kiselgra]

The following code

(lisp
  (defun foo () 0))

works fine using cm c but produces lengthy warnings with cm c++:

   Duplicate definitions in ((and (&rest rest) (list* 'common-lisp:and rest))
                             (or (&rest rest) (list* 'common-lisp:or rest))
                             (not (&rest rest) (list* 'common-lisp:not rest))
                             (> (&rest rest) (list* 'common-lisp:> rest))
                             (< (&rest rest) (list* 'common-lisp:< rest))
                             (set (&rest rest) (list* 'common-lisp:set rest))
    ...

It seems that the C++ symbols are just pushed onto the list of C symbols, causing duplication for symbols defined for both (eg decl)