Im pretty sure this is what happened:
You ran the setup script and said y to everything.
The engine and front-end are on 2.1, the latest stable version.
Then you re-installed the front-end but forgot that detail.
I would have picked that up, but the commit message to the latest commit on 2.1 is the same as the master branch because it was a patch to both branches and I didn't ask for the commith hash.