False boolean values found when using ng-show/ng-hide

Re-opening this ticket from a year ago. This is clearly a bug in Angular, and should not have been closed.

If you type 'n', 'no', 'f', 'false' or '0' into the search field, ng-hide / ng-show is triggered incorrectly.

Here is an updated plunker illustrating the issue: 
http://plnkr.co/U99tFB

Original ticket:
https://github.com/angular/angular.js/issues/1229
