Version 1.49 works fine, but 1.50 (and 1.51) gives me this when I start Slime:
---8<--- (From *Messages* and the Slime-repl:) Polling "/tmp/slime.8009".. (Abort with `M-x slime-disconnect'.) [2 times] Connecting to Swank on port 41288.. Disconnected. error in process filter: slime-state/event-panic: The SLIME protocol reached an inconsistent state. error in process filter: The SLIME protocol reached an inconsistent state.
The event was: (:new-features ("ASDF" "MK-DEFSYSTEM" "COMMON-LISP-CONTROLLER" "PCL-STRUCTURES" "PORTABLE-COMMONLOOPS" "PCL" "PYTHON" "PENTIUM" "I486" "LINKAGE-TABLE" "MP" "GENCGC" "CMU18" "CMU18E" "RELATIVE-PACKAGE-NAMES" "CONSERVATIVE-FLOAT-TYPE" "RANDOM-MT19937" "HASH-NEW" "X86" "LINUX" "GLIBC2" "UNIX" "COMMON" "CMU" "NEW-COMPILER" "COMMON-LISP" "ANSI-CL" "IEEE-FLOATING-POINT"))
The state stack was: (slime-evaluating-state slime-idle-state) ---8<---
This is with Emacs 21.3+1-4 and CMUCL 18e-7 on Debian.