[git] How to track untracked content?

I recently encountered this problem while working on a contract project(deemed classified). The system in which I had to run the code did not have internet access, for security purposes of course, and so installing dependencies, using composer and npm, was becoming huge pain.

After much deliberation with my colleague, we decided to just wing it and copy paste our dependencies rather than doing composer install or npm install.

This led us to NOT add vendors and npm_modules in gitignore. This is when I encountered this problem.

Changed but not updated:
modified:   vendor/plugins/open_flash_chart_2 (modified content, untracked content)

I googled this a bit and found this helpful thread on SO. Not being too much of a pro in Git, and being a little intoxicated while working on it, I just searched for all the submodules in the vendors folder

find . -name ".git"

This gave me some 4-5 dependencies that had git on them. I removed all these .git folders and voila, it worked. I knows it's hack, and not a very geeky one anyways. O Gods of SO, please forgive me! Next time I promise to read up on gitlinks and obey O mighty Linus Tovalds.