swank-clisp.lisp (defvar *external-format-to-coding-system* ...) has the following line:
((:charset "iso-8859-1" :latin-1) "latin-1" "iso-latin-1" "iso-8859-1")
Is the car correct? It is used as an argument to ext:make-encoding in (defimplementation find-external-format (coding-system) ...) and it does not satisfy its lambda list (see http://clisp.cons.org/impnotes/encoding.html#make-encoding)
Mirko