We learned this during the conference...
The procedure is to use git to track and change versions. There are basically three steps:
1. Change to another webwork version, say develop. Within the /opt/webwork/webwok2 directory, sudo git checkout develop (sudo may not be needed, it was for me)
2. Change the pg version. Within /opt/webwork/pg
sudo git checkout develop
3 Run OPL update: Within /opt/webwork/webork2/bin
sudo -E ./OPL-update
To switch back to master, replace develop with master in first two steps. To see what branch you are using, git branch or git branch -a.