now I need to update the submodules into the project.
The parent repo only records SHA1 (in a special gitlink entry, mode 160000)
You can, in your rails4
branch, update your .gitmodules in order to ask your submodule to checkout/update their rails4
branch: see "Git submodules: Specify a branch/tag" for the full process: it starts with:
cd /path/to/your/parent/repo
git config -f .gitmodules submodule.<path>.branch <branch>
That will allow for a git submodule update --recursive --remote
to update the rails4
branch in those submodules.