don't halloo until you are out of the woods

Don't consider or proclaim a problem solved until you are sure that it is completely, permanently resolved, as more issues might crop up before then. (To "halloo" means to shout or yell in a boisterous way, especially to catch someone's attention.) A: "Acquiring this account will solve all our financial worries." B: "Hmm, don't halloo until you are out of the woods. If they pull out or can't pay us in time, we'll still be in trouble." A: "I'm pretty confident that the treatment will eliminate the cancer very quickly." B: "Don't halloo until you're out of the woods, Doc. That cancer could still spread to other parts of the body." I know you've finally started making progress, but this is a complex problem. Don't halloo until you are out of the woods.