If you say git meta open "foo", we interpret it as "git meta open
./foo". Then, if it's already open, we say, "Sorry, $repo is already
open" (where $repo is the submodule that your cwd is inside. But you
might have meant "git meta open $(git meta root)/foo", and thus you
might be confused. Note that this can happen whether or not "./foo"
exists -- we don't check that because in the case that it doesn't,
checking would require half-opening the repo.
In this patch, we notice that you have done this, and say, "$repo (for
filename foo) is already open".
If you say git meta open "foo", we interpret it as "git meta open ./foo". Then, if it's already open, we say, "Sorry, $repo is already open" (where $repo is the submodule that your cwd is inside. But you might have meant "git meta open $(git meta root)/foo", and thus you might be confused. Note that this can happen whether or not "./foo" exists -- we don't check that because in the case that it doesn't, checking would require half-opening the repo.
In this patch, we notice that you have done this, and say, "$repo (for filename foo) is already open".