I think lars is plagued with a case of Gitus submodulusism. It's painful but no fatal. 
Something is changing in webapp-django/vendor whenever he runs the Makefile. 
Either that or what it could be, just a theory; If you do `git pull origin master` it will move the git needle pointer to a different revision but it won't update the submodules. That means that you're now with a "dirty" repository and if you do `git commit -a -m "some message"` that dirty state gets included in the commit message or something.