Some important changes to Known were merged in over the weekend.
Most notably, (most) external dependencies are now managed and installed via Composer, and not included natively in the repository itself.
This makes updates easier to manage, but it does mean that if you are installing from (or more importantly, upgrading from) the git repository directly, you will need to perform an extra step.
cd /path/to/known; composer install
This is particularly important if you’re upgrading, and your site is a checkout of the git repo.
I’m reminded that I desperately need to upgrade everything on my install…