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
- Bug#1051069: slime: 2.2.28 gives "Lisp connection clos... Gijs Hillenius
- Bug#1051069: slime: 2.2.28 gives "Lisp connection... Gijs Hillenius
- Bug#1051069: fixed by cleaning .cache/common-lisp/ Gijs Hillenius
