node-gyp and binding,gyp not default_configuration

I am trying to compile a module as release by defaults, I set at buinding.gyp the

  'target_defaults': {
    'default_configuration': 'Release'
   },

But always I got as BuildType="Debug"

gyp info it worked if it ends with ok
gyp info using node-gyp@0.8.4
gyp info using node@0.8.12 | linux | x64
gyp info spawn make
gyp info spawn args [ 'BUILDTYPE=Debug', '-C', 'build' ]
make: Entering directory `/home/ammarch/colaboration/node-webworker-threads/build'
make: Nothing to be done for `all'.
make: Leaving directory `/home/ammarch/colaboration/node-webworker-threads/build'
gyp info ok 

Check the package.json scripts:

if you have --debug in there, this will force a debug build anyway.

"scripts": {
  "install": "node-gyp --debug rebuild",
  "test": "mocha tests"
},

Removing --debug should fix it.