make-load-form issue since 20.4.24

Describe the problem here.

Since ECL 20.4.24, there is an issue where in a particular instance, loading/compiling a file complains about a missing make-load-form specialization, although there is no corresponding object being embedded in the source code.

I have tried very hard to boil this issue down to a simple test case, but I failed to distill this to a simple example. All simple examples seem to work correctly.

So in order to reproduce the problem, you would have to clone AspectL from https://github.com/pcostanza/aspectl/

Then cd to aspectl/test/, start ECL, then execute (load "ml13-test.lisp"). I see the following output:

> (load "ml13-test.lisp")

Condition of type: SIMPLE-ERROR
No adequate specialization of MAKE-LOAD-FORM for an object type SPECIAL-FUNCTION

(AspectL is a library that implements a number of advanced CLOS MOP extensions, so this is very likely related to recent CLOS MOP changes - but that's just a guess. AspectL is not part of Quicklisp because it has been superseded by ContextL, but I'm still using it to test CLOS MOP compliance of CL implementations.)

Describe expected result and what provide the output you got.

This problem didn't occur in previous versions of ECL, and doesn't occur in other CL implementations that support AspectL.

Provide details regarding ECL version (or preferably commit), operating system and if revelant the build options and versions of the build tools.

     VERSION "20.4.24"
      VCS-ID "UNKNOWN"
          OS "Darwin"
  OS-VERSION "19.5.0"
MACHINE-TYPE "x86_64"
    FEATURES (:CX-THREADS :CONTEXTL :DYNAMIC-WIND :CLOSER-MOP :QUICKLISP :ASDF-PACKAGE-SYSTEM :ASDF3.1 :ASDF3 :ASDF2 :ASDF :OS-MACOSX :OS-UNIX :NON-BASE-CHARS-EXIST-P :ASDF-UNICODE :WALKER :CDR-1 :CDR-5 :DARWIN :FORMATTER :CDR-7 :ECL-WEAK-HASH :LITTLE-ENDIAN :LONG-LONG :UINT64-T :UINT32-T :UINT16-T :COMPLEX-FLOAT :LONG-FLOAT :UNICODE :DFFI :CLOS-STREAMS :CMU-FORMAT :UNIX :ECL-PDE :DLOPEN :CLOS :THREADS :BOEHM-GC :ANSI-CL :COMMON-LISP :FLOATING-POINT-EXCEPTIONS :IEEE-FLOATING-POINT :PACKAGE-LOCAL-NICKNAMES :CDR-14 :PREFIXED-API :FFI :X86_64 :COMMON :ECL)