b57 pcl-cvs ediff error

`pcl-cvs-version' is a variable declared in Lisp. -- loaded from "/usr/local/lib/xemacs/xemacs-packages/lisp/pcl-cvs/pcl-cvs.elc" Value: "1.05-CVS-$Name: $" `emacs-version' is a variable declared in Lisp. -- loaded from "/usr/local/src/xemacs-21.0-b57/lisp/version.el" Value: "21.0 \"Poitou\" XEmacs Lucid" Signaling: (wrong-type-argument stringp nil) expand-file-name(nil) find-file-noselect(nil) cvs-run-ediff-on-file-descriptor([[[... #1 ...] #0 (WRAPPER . ...)] [#0 [#1 ... ...] (WRAPPER . ...)] (WRAPPER . [#<marker at 620 in *cvs* 0x8a2fe64> ...])]) run-ediff-from-cvs-buffer(620) cvs-mode-ediff(620) call-interactively(cvs-mode-ediff)