Describe the bug
Using git submodules as imports in devenv.yaml results in an error.

To reproduce

1. Create a git repository
2. Add git submodules

git submodule add <BACKEND_URL> backend
git submodule add <FRONTEND_URL> frontend

4. Run devenv init
5. Change devenv.yaml
   https://gist.github.com/bdj/8cceb2af38c6a6cde33148619984aaf2
6. Run devenv shell

Fails with the following output
https://gist.github.com/bdj/6275dd3c7f9ed85e800c0d17638ce9c0

Version
devenv 1.0.1 (aarch64-darwin)