The steps, typically, would be:
git fetch --all
git checkout working-1.6
The fetch is probably the more important as it will pull in any new branches and tags. It will not clean older branches though.
@skasai In addition/instead of using iptables once could restrict nfs access on the nfs share level too. I understand you have a working build so don’t change just because of this, but be aware that with NFS v3 you can restrict mounting the NFS share based on ip address/subnet range.