WP8 fails on: phonegap test wp8 --test

gistfile1.txt

$ phonegap run wp8 --test
[phonegap] detecting Windows Phone 8 SDK environment...
[phonegap] using the local environment
[phonegap] compiling Windows Phone 8...

fs.js:543
  return binding.rename(pathModule._makeLong(oldPath),
                 ^
Error: EPERM, operation not permitted 'c:\Users\timki_000\repo\phonegap-app\www-
backup'
    at Object.fs.renameSync (fs.js:543:18)
    at Object.<anonymous> (c:\Users\timki_000\repo\phonegap-app\.cordova\hooks\b
efore_prepare\test-runner.js:28:8)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)
    at startup (node.js:119:16)
    at node.js:902:3
{ name: 'CordovaError',
  message: 'Hook failed with error code 8: c:\\Users\\timki_000\\repo\\phonegap-
app\\.cordova\\hooks\\before_prepare\\test-runner.js' }
   [error] Hook failed with error code 8: c:\Users\timki_000\repo\phonegap-app\.
cordova\hooks\before_prepare\test-runner.js