Nested submodule checkout

Dear git developers,

I stumbled into this situation from which it was a bit painful to recover:

-> test script:

    mkdir ploum
    cd ploum
    git init
    echo 'foo' > foo
    git add foo
    git commit -m foo
    git branch nosubmodules

    mkdir plam
    cd plam
    git init
    echo 'bar' > bar
    git add bar
    git commit -m bar

    mkdir plim
    cd plim
    git init
    echo 'baz' > baz
    git add baz
    git commit -m baz

    cd ..
    git submodule add ./plim
    git commit -am 'Add submodule plim'

    cd ..
    git submodule add ./plam
    git commit -am 'Add submodule plam'

    git checkout nosubmodules
    git checkout --recurse-submodules master

-> The result is as follow:

Initialized empty Git repository in /data/dams/var/tmp/ploum/.git/
[master (root-commit) ec7c09a] foo
 1 file changed, 1 insertion(+)
 create mode 100644 foo
Branch 'nosubmodules' set up to track local branch 'master'.
Initialized empty Git repository in /data/dams/var/tmp/ploum/plam/.git/
[master (root-commit) 35e6696] bar
 1 file changed, 1 insertion(+)
 create mode 100644 bar
Initialized empty Git repository in /data/dams/var/tmp/ploum/plam/plim/.git/
[master (root-commit) b4712c1] baz
 1 file changed, 1 insertion(+)
 create mode 100644 baz
Adding existing repo at 'plim' to the index
[master 989c11d] Add submodule plim
 2 files changed, 4 insertions(+)
 create mode 100644 .gitmodules
 create mode 160000 plim
Adding existing repo at 'plam' to the index
[master 5b34041] Add submodule plam
 2 files changed, 4 insertions(+)
 create mode 100644 .gitmodules
 create mode 160000 plam
Migrating git directory of 'plam' from
'/data/dams/var/tmp/ploum/plam/.git' to
'/data/dams/var/tmp/ploum/.git/modules/plam'
Migrating git directory of 'plam/plim' from
'/data/dams/var/tmp/ploum/plam/plim/.git' to
'/data/dams/var/tmp/ploum/.git/modules/plam/modules/plim'
Switched to branch 'nosubmodules'
Your branch is behind 'master' by 1 commit, and can be fast-forwarded.
  (use "git pull" to update your local branch)
fatal: exec '--super-prefix=plam/plim/': cd to 'plim' failed: No such file or directory
error: Submodule 'plim' could not be updated.
error: Submodule 'plam/plim' cannot checkout new HEAD.
error: Submodule 'plam' could not be updated.
M	plam
Switched to branch 'master'

As you can see, the nested plim submodules could not be recreated since the folder does not exists yet in the 'nosubmodules' branch. This makes the 'plam' submodule update fails, and in the following state

Unstaged changes after reset: D .gitmodules D bar D plim

-> To recover

In the folder plam, do a `git reset` followed by a `git reset --hard` (`git reset --hard` directly does not work: fatal: exec '--super-prefix=plim/': cd to 'plim' failed: No such file or directory)

Indeed the first reset, which puts .gitmodules back in the index, is what allows to do the `git submodule update` implied by `git reset --hard`. Since (from what I understand) the path is only read from .gitmodules and not from the .git/config (where there are only the submodules name which are distinct from the path), this explain the failures observed.

Note that I wasn't able to reproduce in this small examples, but when trying to repair I also add some strange errors of the form '.git is not a git directory' (where .git was a pseudo symlink gitdir: ../.git/modules/plam).

-> Question

My usage is probably non standard (I have quite a lot of nested submodules), so I had a hard time to recover from this checkout. Is there a better way? Would it be possible to make nested submodules checkout of this form work out of the box?

Thanks! Damien Robert