Error: command plug is breaking by node 8

I can't execute branch 1.6 (commit 9989856c) after use the plug command

$ bin/duniter direct_start
module.js:538
    throw err;
    ^

Error: Cannot find module 'co'
    at Function.Module._resolveFilename (module.js:536:15)
    at Function.Module._load (module.js:466:25)
    at Module.require (module.js:579:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (/home/elois/dev/duniter/bin/duniter:4:12)
    at Module._compile (module.js:635:30)
    at Object.Module._extensions..js (module.js:646:10)
    at Module.load (module.js:554:32)
    at tryModuleLoad (module.js:497:12)
    at Function.Module._load (module.js:489:3)