title: Rails Sorcery Bug? Creates Duplicate User Accounts
body: <p>The example sorcery code shown on github appears to me to create duplicate accounts if it is extended to allow for multiple sign in methods (which is the whole point of oauth).  You can see in the snipit here that create_from() will be called if login_from() does not succeed.</p>
  
  <p>GITHUB AT at <a href="https://github.com/NoamB/sorcery-example-app/blob/master/app/controllers/oauths_controller.rb" rel="nofollow">https://github.com/NoamB/sorcery-example-app/blob/master/app/controllers/oauths_controller.rb</a></p>
  
  <pre><code>def callback
  provider = params[:provider]
  begin
  if @user = login_from(provider)
    redirect_to root_path, :notice =&gt; "Logged in from #{provider.titleize}!"
  else
    begin
      @user = create_from(provider)
  </code></pre>
  
  <p>Investigating the source code for create_from in all cases a new User Account record will be created.  This would not be correct, if a User account record already exists.</p>
  
  <p>My question:  What sorcery methods should be called on the first facebook connect, if a User account has been created by some means other than facebook.  login_from will fail, and create_from will generate a duplicate usser record?</p>