npm adduser not generate _auth token

Using npm (2.7.3) adduser produce unknown content in ~/.npmrc

Instead of _auth and email I get:

//registry.npmjs.org/:_password=balbalblabnlabkabak
//registry.npmjs.org/:username=myUsername
//registry.npmjs.org/:email=my@mail.com
//registry.npmjs.org/:always-auth=false

This work fine on my local machine, but I need the _auth token for remote publishing on wercker or travis.

I have no idea why I can't get _auth token. Already google for it without luck. Test to use _password as _auth but i don't work.

Anyone who can help?