+ * incompatible change: The --disable-debugger command line
+ option now clobbers the debugger at a more fundamental
+ level, by redefining #'INVOKE-DEBUGGER instead of by
+ rebinding *DEBUGGER-HOOK*. The main difference is that BREAK
+ is specified by ANSI to ignore *DEBUGGER-HOOK* and
+ INVOKE-DEBUGGER regardless. Under the old system, BREAK would
+ enter the debugger REPL and then suffer recursive errors
+ because *DEBUG-IO* is also messed up in --disable-debugger mode;
+ while under the new system, BREAK in --disable-debugger mode
+ terminates the system just as an unhandled error would.