bug#50975: 28.0.60; mh-utils-tests fail with native compilation

[Andrea Corallo]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Ken Brown <kbrown@cornell.edu>
>> Date: Sat, 2 Oct 2021 14:49:04 -0400
>> 
>> Most of the tests in mh-utils-tests fail if I build the emacs-28 branch on 
>> Cygwin with native compilation:
>> 
>> $ make -C test mh-utils-tests
>> make: Entering directory 
>> '/home/kbrown/src/emacs/x86_64-emacs-28-native-lisp/test'
>> make[1]: Entering directory 
>> '/home/kbrown/src/emacs/x86_64-emacs-28-native-lisp/test'
>>    GEN      lisp/mh-e/mh-utils-tests.log
>> Running 16 tests (2021-10-02 14:13:13-0400, selector ‘(not (tag :unstable))’)
>> No MH variant found on the system
>> call-process mock unexpected arglist (emacs --batch -l 
>> /tmp/emacs-int-comp-subr--trampoline-66696c652d6469726563746f72792d70_file_directory_p_0-rg5Ucy.el)
>> call-process mock unexpected arglist (emacs --batch -l 
>> /tmp/emacs-int-comp-subr--trampoline-66696c652d6469726563746f72792d70_file_directory_p_0-f6P2ZU.el)
>> Test mh-folder-completion-function-02-empty backtrace:
>
> Andrea, please look into this when you have time.
>
> Thanks.

Yep will have a look, I'd bet is `file-directory-p' being redefined with
a incompatible lambda list.

  Andrea