flatten: true not working

[markusfalk]

svg2png: {
      app: {
        files: [{
          expand: true,
          flatten: true,
          cwd: 'components/app',
          src: ['**/*.svg'],
          dest: 'build/assets/img'
        }]
      }
    },

when options set to flatten:true it still keeps all paths in dest

thanks!