Subject: 27.0; `dired-change-marks': args should not be optional

From: Drew Adams <[email-masked]>
Date: Sun, 24 Dec 2017 09:58:02 -0800 (PST)

1. There is no use of this function in the Emacs Lisp sources that needs
   to have the args be optional.

2. If (dired-change-marks) is evaluated then you get an error:

   Debugger entered--Lisp error: (error "Format specifier doesn't match
                                         argument type") 
    format("\n%c" "nil")
    dired-change-marks()
    eval((dired-change-marks))

This bug is apparently quite old - it is present in Emacs 20, for
example.

In GNU Emacs 27.0.50 (build 4, x86_64-w64-mingw32)
 of 2017-12-21
Repository revision: b1cf262a79463f28164ea1c2ffee3c657ce02ea4
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --without-dbus --host=x86_64-w64-mingw32
 --without-compress-install -C 'CFLAGS=-O2 -static -g3'
 host_alias=x86_64-w64-mingw32 PKG_CONFIG_PATH=/mingw64/lib/pkgconfig'