Re: [PATCH 3/3] git-checkout.txt: a note about multiple checkout support for submodules

> The goal seems to be using multiple checkouts to reduce disk space.
> But we have not reached an agreement how things should be. There are a
> couple options.
> 
>  - You may want to keep $SUB repos elsewhere (perhaps in a central
>    place) outside $SUPER. This is also true for nested submodules
>    where a superproject may be a submodule of another superproject.
> 
>  - You may want to keep all $SUB repos in $SUPER/modules (or some
>    other place in $SUPER)
> 
>  - We could even push it further and merge all $SUB repos into $SUPER
>    instead of storing them separately. But that would at least require
>    ref namespace enabled.
> 
> On top of that, git-submodule.sh expects $GIT_DIR/config to be
> per-worktree, at least for the submodule.* part. Here I think we have
> two options, either update config.c to also read
> $GIT_DIR/config.worktree (which is per worktree) in addition to
> $GIT_DIR/config (shared) and store worktree-specific vars in the new
> place, or update git-submodule.sh to read/write submodule.* directly
> from $GIT_DIR/config.submodule (per worktree).
> 
> These take time to address properly. Meanwhile, make a note to the
> user that they should not use multiple worktrees in submodule context.