bug#27528: 26.0.50; load-path initialisation is wrong when Emacs is launched in batch mode from a console inside another Emacs

[Eli Zaretskii]

> From: vincent.belaiche@gmail.com (Vincent Belaïche)
> Date: Thu, 29 Jun 2017 12:30:37 +0200
> Cc: Vincent Belaïche <vincent.belaiche@gmail.com>
> 
> The content of load-path-outside-other-emacs.txt is as follows (all the
> content is stdout):
> 
> --8<----8<----8<----8<----8<-- begin -->8---->8---->8---->8---->8----
> (c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/vc 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/url 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/textmodes 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/progmodes 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/play 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/org 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/nxml 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/net 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/mh-e 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/mail 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/leim 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/language 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/international 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/image 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/gnus 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/eshell 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/erc 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/emulation 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/emacs-lisp 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/cedet 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/calendar 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/calc 
> c:/Nos_Programmes/GNU/Emacs/share/emacs/26.0.50/lisp/obsolete)--8<----8<----8<----8<----8<--
>   end  -->8---->8---->8---->8---->8----
> 
> To me this output is correct.
> 
> 3) From a DOS shell inside emacs-25 instance, launched by `M-x shell', I
> launch the following command, that is equivalent to the first one:
> 
> --8<----8<----8<----8<----8<-- begin -->8---->8---->8---->8---->8----
> %EMACS% --batch -Q --eval "(princ load-path)" ^
>    > %TEMP%\load-path-inside-emacs-dos.txt 2>&1 
> --8<----8<----8<----8<----8<--  end  -->8---->8---->8---->8---->8----
> 
> Then I get the following output:
> 
> --8<----8<----8<----8<----8<-- begin -->8---->8---->8---->8---->8----
> (c:/Nos_Programmes/GNU/Emacs_build20170614/share/emacs/26.0.50/lisp)Warning: 
> arch-dependent data dir 
> 'c:/Nos_Programmes/GNU/Emacs_build20170614/libexec/emacs/26.0.50/i686-pc-mingw32/':
>  Permission denied
> Warning: Lisp directory 
> 'c:/Nos_Programmes/GNU/Emacs_build20170614/share/emacs/26.0.50/lisp': Invalid 
> argument
> Warning: Could not find simple.el or simple.elc
> --8<----8<----8<----8<----8<--  end  -->8---->8---->8---->8---->8----
> 
> The text up to `)' is stdout, and the remainder is stderr. To me this
> output is wrong.

I think this is because Emacs 25 exports to the environment of the
subordinate Emacs its value of emacs_dir, which then points the
subordinate Emacs at the directory where Emacs 25 lives.

Emacs 26 fixed that problem, AFAIR, so I think if you do it the other
way around, i.e. invoke Emacs 25 from inside Emacs 26, you will see
the expected behavior.