Fetch stack.yaml extra-packages git submodules

[iand675]

I attempted to pull in a fork of proto-lens that I'm working on to ensure that it worked for an upstream project, and found that it failed to build proto-lens-protbuf-types due to a dependency on a submodule. When using stack directly, it always fetches submodules, so this PR updates calls to fetchGit for stack to do the same:

To repro: add this stanza to a stack.yaml and depend on proto-lens-protobuf-types in the Haskell package. Without this PR, it'll fail because the .proto files are used directly from the official Google protobuf repo by cloning it as a submodule.

extra-deps:
- git: git@github.com:iand675/proto-lens.git
  commit: 38b1ab1d6785c36694245b19ce6a85ee6869b04a
  subdirs:
  - proto-lens
  - proto-lens-protoc
  - proto-lens-protobuf-types
  - proto-lens-runtime
  - proto-lens-setup
  - proto-lens-json

With this PR, that issue doesn't crop up. Unfortunately, I run into a different issue, which is:

Error: couldn't find the executable "protoc" in your $PATH.
   Follow the installation instructions at https://google.github.io/proto-lens/installing-protoc.html .

So I guess unrelated to the exact change of this PR, can anyone help me understand how to override buildInputs and other details of the packages being pulled in from the stack.yaml?

[angerman]

@iand675 sorry for the late reply. Can you try to merge master into your branch? I'll admit that our stack support is a bit lagging, as we don't have any active stack users at IOG anymore.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.