PARSE-COMPILED-DEBUG-FUN-LAMBDA-LIST failure

[Douglas Katzman]

;; An ignored var with a not ignored supplied-p var borks.
(defun bork (foo &optional (env nil env-p))
  (declare (ignore env env-p))
  (print foo)
  (progn (sb-debug:print-backtrace) 'what))

Backtrace for: #<SB-THREAD:THREAD "main thread" RUNNING {1002C34A03}>
0: ((LAMBDA NIL :IN SB-DEBUG::FUNCALL-WITH-DEBUG-IO-SYNTAX))
1: (SB-IMPL::CALL-WITH-SANE-IO-SYNTAX #<CLOSURE (LAMBDA NIL :IN SB-DEBUG::FUNCALL-WITH-DEBUG-IO-SYNTAX) {1002C978CB}>)
2: (SB-IMPL::%WITH-STANDARD-IO-SYNTAX #<CLOSURE (LAMBDA NIL :IN SB-DEBUG::FUNCALL-WITH-DEBUG-IO-SYNTAX) {1002C9789B}>)
3: (PRINT-BACKTRACE :STREAM NIL :START 0 :FROM :DEBUGGER-FRAME :COUNT NIL :PRINT-THREAD T :PRINT-FRAME-SOURCE NIL :METHOD-FRAME-STYLE NIL)
4: 1
debugger invoked on a TYPE-ERROR in thread
#<THREAD "main thread" RUNNING {1002C34A03}>:
  The value :DELETED is not of type LIST.