ediff-patch-file and ediff-patch-buffer don't work

[Sven Joachim]

The commands ediff-patch-file and ediff-patch-buffer don't work,
signalling the error: Wrong type argument: stringp, nil.

Here is a sample session:

 $ ls -l startup*
 -rw-r--r--  1 sven sven   821 2005-08-19 17:57 startup-patch
 -rw-r--r--  1 sven sven 70699 2005-08-19 18:03 startup.el

Now, in Emacs I tried: M-x ediff-patch-file
Is the patch already in a buffer? (y or n) n
Patch is in file: (default startup-patch) ~/ RET
File to patch (directory, if multifile patch): ~/startup-el

I got the error: Wrong type argument: stringp, nil

With ediff-patch-buffer, it is the same.

My Emacs version is:

 GNU Emacs 22.0.50.1 (i386-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2005-08-15 on debian, modified by Debian


Regards,

Sven