Add key to allow fetching submodules for git repos

• I have searched the issues of this repo and believe that this is not a duplicate.

Issue

Currently, git dependencies do not fetch submodules. This makes dependencies like mypy unusable when installing it from git. I don’t think fetching submodules should be the default behavior, but it would be nice if git dependencies had the option to fetch them. For instance:

[tool.poetry.dependencies]
# Submodules would not be fetched for sqlalchemy-stubs
sqlalchemy-stubs = {rev = "8b45fc4345778e3f08e8a3b53ff71aaaa775e632", git = "https://github.com/dropbox/sqlalchemy-stubs.git"}

[tool.poetry.dev-dependencies]
# Submodules would be fetched for mypy because of submodules = true
mypy = {rev = "47c25263694bae2a577c15d70d2988db2e8e8584", git = "https://github.com/python/mypy.git", submodules = true}

[sdispater]

Maybe Poetry should just always pull submodules for Git dependencies. This would avoid introducing yet another option which would complicate things in the codebase and pulling submodules should not have any side effect that I can think of.

[dbarrosop]

is there any progress on this? I am also having this problem 😦