Update "dindLatest" calculation to be more defensive

Author: tianon

versions.sh

@@ -24,7 +24,8 @@ fi
 versions=( "${versions[@]%/}" )
 
 # "tac|tac" for http://stackoverflow.com/a/28879552/433558
-dindLatest="$(curl -fsSL 'https://github.com/docker/docker/commits/master/hack/dind.atom' | tac|tac | awk -F '[[:space:]]*[<>/]+' '$2 == "id" && $3 ~ /Commit/ { print $4; exit }')"
+dindLatest="$(curl -fsSL 'https://github.com/docker/docker/commits/master/hack/dind.atom' | grep -E 'id.*Commit')"
+dindLatest="$(awk <<<"$dindLatest" -F '[[:space:]]*[<>/]+' '$2 == "id" && $3 ~ /Commit/ { print $4; exit }')"
 
 dockerVersions="$(
 	git ls-remote --tags https://github.com/docker/docker.git \