Commit 538ca8dd65f0075cc65bcca18ed87f66a789290a introduced a second '_guix_complete_subcommand' function, shadowing the existing one, which broke sub-command completion for 'guix system', 'guix import', etc. * etc/completion/bash/guix: Distinguish between '_guix_complete_command' and '_guix_complete_subcommand'. Adjust users to call the right one.