Re: [PATCH] config: use GIT_CONFIG in git config sequence

[Junio C Hamano <gitster@pobox.com>]

Philip Oakley <philipoakley@iee.email> writes:

> Mateusz's original problem was with discovery of these env variables,...

I somehow doubt it.  

Certainly, defeating /etc/gitconfig should be a part of the solution
to the "I want a stable environment to run tests reproducibly,
without getting affected by random settings the testing user may get
affected" problem.  It is not enough to defeat $HOME/.gitconfig (and
its xdg variant).

But I didn't get the feeling that Mateusz was even aware of the need
to defeat the system wide configuration; Mateusz only mentioned and
cared about $HOME/.gitconfig (and its xdg variant).

And the thing is that we do have support for an environment variable
to defeat the system-wide configuration (GIT_CONFIG_NOSYSTEM), but
discovering it would not have been sufficient to solve the "stable
environment for reproducible tests" problem, as we do not have an
environment variable to defeat the global (i.e. per user) one.

So, I do not think the problem was with discovery at all.  The
problem was two levels deep, (1) not realizing the need to defeat
the system wide settings (for which the environment may have been a
good solution once the need to solve that problem got recognised),
and (2) not realizing the need to redirect $HOME for programs other
than git, hence omitting $HOME/.gitconfig from the sequence is not
a sufficient solution.

Having said all that, I addition of GIT_CONFIG_NOGLOBAL (or
GIT_CONFIG_NOUSER) may not be such a bad thing.  We probably will
add GIT_CONFIG_NOLOCAL (or GIT_CONFIG_NOREPOSITORY) to complement
these two if that happens.  I dunno.