Error fetching submodule from submodule

[Jesper Rønn-Jensen <jesperrr@xxxxxxxxx>]

Hi I think I may have found an error in the way git handles a
submodule's submodule. Read further for the example (extracted from a
real project).

* I have a main repository which has some submodules defined.
* One of the submodules is a common submodule which is also included
in one of the other submodules
* When running `git fetch --recurse-submodules` I get an error.

The error is "Could not access submodule 'common_submodule'"

```
$ git --version
git version 2.21.0
```

I created the following script to show (using Git-extras `git create`
to simplify):


```
#!/usr/bin/env bash

if [ "$FORCE" = 'true' ]; then
  rm -rf submodule_experiment
fi

if [ -e submodule_experiment ]; then
  echo FATAL: folder submodule_experiment must not exist. Remove with FORCE=true
  exit 9
fi

mkdir submodule_experiment
pushd submodule_experiment

git setup common_submodule
pushd common_submodule
echo 'common file' > common.txt
git add common.txt
git commit -m 'a file in the common submodule'

popd

git setup other_submodule
pushd other_submodule
git submodule add ../common_submodule
git commit -m 'added submodule to other_submodule'

popd

git setup main_repos
pushd main_repos
git submodule add ../common_submodule
git commit -m 'added submodule to main_repos'

git submodule add ../other_submodule
git commit -m 'added other_submodule to main_repos'


# This line fails with error code 1 "Could not access submodule
'common_submodule'"
git fetch --recurse-submodules

```

Question:
Is this a bug in Git or am I declaring the common submodule in an incorrect way?


-- 

Jesper Rønn-Jensen
Nine A/S
Mobile: +45 2989 1822
Blog http://justaddwater.dk/
jesperrr@xxxxxxxxx (Private e-mail and Google Talk IM)