It took me a while to piece together all the steps to get a working V11 installation from the git staging branch. I do this install on a fresh Digital Ocean Ubuntu 16.04 droplet, 1cpu, 2GB ram.
###Initial Production Setup
sudo apt-get update && sudo apt-get install python-dev python-setuptools build-essential && wget https://raw.githubusercontent.com/frappe/bench/master/playbooks/install.py && sudo python install.py --production --user frappe
###Specify a frappe user password
sudo passwd frappe
###Make frappe sudo user
usermod -aG sudo frappe
###Log into a new terminal as frappe and go into the erpnext app folder
cd ~/frappe-bench/apps/erpnext
###Set upstream git
git config remote.upstream.fetch "+refs/heads/*:refs/remotes/upstream/*"
###Log into your site and set up a company through the setup wizard (otherwise patches will fail later in this guide)
###Change to Bench directory
cd ~/frappe-bench
###Switch to staging branches or whatever branch you want.
bench switch-to-branch staging frappe
bench switch-to-branch staging erpnext
###Set up bench (use your own site name if you are not using the default site1.local)
bench setup requirements
bench update --patch
###It seems like everything below was done with the update command above, but I did them anyway:
bench --site site1.local migrate
###Confirm changes
bench version
###Restart supervisor
bench restart