Git submodules not initialised with remote modules/sources

[eysi09]

Bug

Submodules not included with remote sources/modules.

Current Behavior

When importing remote modules/sources via the respositoryUrl directive, submodules are not initialised.

Expected behavior

Submodules should be initialised and work as expected when importing remote modules/sources.

Reproducible example

N/A

Suggested solution(s)

Garden should initial submodules after cloning remote repositories. E.g. with git submodule update --init --recursive.

Furthermore, Garden should update the submodules when garden update-remote source|module is run, e.g. with git submodule update --recursive --remote.

Additional context

This was pointed out as an issue in our community Slack.

Your environment

garden version:

0.8.1

kubectl version

Client Version: version.Info{Major:"1", Minor:"10", GitVersion:"v1.10.3", GitCommit:"2bba0127d85d5a46ab4b778548be28623b32d0b0", GitTreeState:"clean", BuildDate:"2018-05-21T09:17:39Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"10", GitVersion:"v1.10.3", GitCommit:"2bba0127d85d5a46ab4b778548be28623b32d0b0", GitTreeState:"clean", BuildDate:"2018-05-21T09:05:37Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"linux/amd64"}

docker version

Client: Docker Engine - Community
 Version:           18.09.0
 API version:       1.39
 Go version:        go1.10.4
 Git commit:        4d60db4
 Built:             Wed Nov  7 00:47:43 2018
 OS/Arch:           darwin/amd64
 Experimental:      false

Server: Docker Engine - Community
 Engine:
  Version:          18.09.0
  API version:      1.39 (minimum version 1.12)
  Go version:       go1.10.4
  Git commit:       4d60db4
  Built:            Wed Nov  7 00:55:00 2018
  OS/Arch:          linux/amd64
  Experimental:     true