Initialise env for login shells in bash
Initialise env for login shells in bash

Previous behaviour was wrong: update .bash_profile if it exists, .bashrc otherwise.
This now respects loading order of bash for login shells to be sure we update
the file that will be loaded.

Still, bash loads distinct files, exclusively, in login and non-login mode: either
one of the profiles, or .bashrc. Unless you include one from the other, which many
do, but you can't rely on that. We may end up having to load variables from _both_
files to handle both cases, loading them twice being harmless ; but I hope we don't
need to.

In non-interactive mode, bash doesn't load any specific files (except if BASH_ENV
is defined, but defining it would be the same problem) so we're out of luck anyway.

abate/opam,abate/opam