bug#42600: /etc/profile not being sourced from interactive non-login shell

[Kyle Andrews <kyle.c.andrews@gmail.com>]

Despite what it says in my ~.bashrc~, if I start a shell from Emacs with
the elisp below, then `guix describe` does not work:

  (let ((default-directory "/ssh:me@remote:/home/me"))
      (shell "*shell<remote>*"))

Of course, if I start a shell normally with ~M-x shell~ in Emacs, then
type out the ssh command, ~/etc/profile~ does get sourced.

I learned about this by following the advice of nckx from IRC, placing
`set -x` in my .bash_profile. Following the former routine in Emacs I
see nothing, but with the explicit ssh call I do see all the commands
echo'd.

Is this a bug in Guix or Emacs? In other words, should the Bash
configuration files be extended to handle this case? I thought my system
might be broken, but nckx showed me that I could just `. /etc/profile`
and then guix describe started working again.

Best Regards,
Kyle