title: rails 5 "password" disappears from params
body: <p>(This is <em>not</em> about filtered parameters in logfiles.)</p>
  
  <p>I have in my view</p>
  
  <blockquote>
    <p>&lt;%= password_field_tag :password, '', autofocus: true, class: 'form-control' %&gt;</p>
  </blockquote>
  
  <p>and then in my controller</p>
  
  <blockquote>
    <p>@password = params[:password]</p>
  </blockquote>
  
  <p>In Rails 4 I can use @password to authenticate, all works fine.</p>
  
  <p>In Rails 5, params does NOT contain :password anymore. If I change :password to :password1 in view and controller, all is fine, so somehow :password is filtered out.</p>
  
  <p>I checked for config.filter_parameters (which controles log file filtering) - removed 'password' from it, but it did not influence this behavior.</p>
  
  <p>What am I missing?</p>