bug#72294: 29.2; Emacs --init-directory=... puts user-init-file elsewhere

[Sean Devlin <spd@toadstyle.org>]

Hi,

> I don't think this is a bug.

Fair enough.

> May I ask why you needed to use this option?  It should not be
> generally needed.

Lately, I run Emacs from the emacs-30 branch with some local tweaks. I
found a bug in Org, and I was trying to reproduce it in a stable version
of Emacs with default configuration. The bug is in Org 9.7+, which is
newer than what ships in Emacs 29.

Since I knew I would need to install a package, I checked the manual for
the command-line flags to specify the user-emacs-directory, and I found
the --init-directory option. I opened an instance of Emacs 29.2 with
--init-directory=/tmp/bug, and I installed Org via ELPA.

Then, for an unrelated task, I opened an instance of my main Emacs
installation, and I was surprised to see it load without any of my
configuration. I discovered the Emacs 29 instance had written a file to
~/.emacs, shadowing my own configuration in ~/.emacs.d/init.el. That it
wrote the user-init-file outside the user-emacs-directory I specified
was surprising to me.