Methinks that it was more like the oft-maligned Neville Chamberlain deal where the White Council came back with a promise from Sauron that he would pack up and go and then put the place up for sale or rent. The base master of lies probably got the Council on the hook for moving expenses.
Another one of Elrond's 'fruitless victories.'
However it happened, Gandalf still for a time believed that Sauron was driven out by Saruman (even though Sauron planned to leave anyway).