Bug#1051069: fixed by cleaning .cache/common-lisp/

[Gijs Hillenius <gijs@hillenius.net>]

It looks like I managed to resolve this by cleaning out

.cache/common-lisp/

which forces the rebuilding of

.cache/common-lisp/2.3.7.debian-linux-x64/

when I restarted Emacs, and M-x slime