[#4818] don't error if tool doesn't exist any more
[#4818] don't error if tool doesn't exist any more

heiths/allura,lym/allura-git,apache/allura,heiths/allura,lym/allura-git,heiths/allura,apache/incubator-allura,apache/allura,lym/allura-git,apache/allura,apache/allura,lym/allura-git,heiths/allura,apache/incubator-allura,apache/allura,apache/incubator-allura,heiths/allura,lym/allura-git,apache/incubator-allura