* emacs/guix-command.el (guix-command-improve-environment-argument): Use
"E" for '--expose' and "S" for '--share' to distinguish them from
'--expression' and '--system' accordingly. Make '--ad-hoc' an option
taking packages instead of a simple switch.
(guix-command-rest-argument): Complete shell command instead of
packages for '--' argument.
(guix-command-additional-arguments): Add fake 'packages' argument.
New variable.
(guix-command-additional-arguments): Use it.
(guix-command-post-process-environment-packages,
guix-command-post-process-environment-ad-hoc): New functions.
(guix-command-post-processors): Add "environment" command with the new
argument processors.
8b341eb05d