Hello emacs-devel,

below is a patch trying to address old bug #15539.

It introduces an EMACS_USER_DIRECTORY environment variable which (if
present) has two effects:
1- it provides a custom value for `user-emacs-directory' (instead of
the default `~/.emacs.d').
2- it instructs emacs to look for the initialization file in the
provided directory (instead of `~USER/.emacs.d')

As explained in the bug's discussion, this covers more use cases than
simply symlinking ~/.emacs.d. Here are for example a few words about
my use case: at work, I try to maintain a sensible set of init files
for my co-workers to use (with the very outdated default version that
we have installed by default on our systems: 23.2). On the other hand,
on my machine, I maintain a locally-installed Emacs version that is
more up-to-date. In order to maintain both sets of init files, I need
to be able to run
both versions of Emacs at the same time, which prevents me from
symlinking ~/.emacs.d/
There are also reddit[1] and stackexchange[2] questions hinting at the
same kind of use.

Please do not hesitate to comment and criticize the patch; this is my
first time and I might very well have overlooked some details.

Thanks in advance,
   François


[1] http://www.reddit.com/r/emacs/comments/2y1b3a/how_can_i_easily_keep_different_emacsd_folders/

[2] http://emacs.stackexchange.com/q/4253/221