title: Owin external login action "Challenge" redirect always to login page
body: <p>I have the same problem as described in this post: "<a href="https://stackoverflow.com/questions/23359713/first-external-login-attempt-redirects-back-to-login-action-second-one-works">First external login attempt redirects back to login action, second one works</a>" </p>
  
  <p>For him it works at second try but for me it's not working at all, he mentioned in his post that he found the reason but I don't understand how he solved it, I searched a lot with no hope :( </p>
  
  <p>If I create a standalone MVC project with Owin membership everything will work as expected, but when I put it in an existing MVC project it redirects to login page each time I tried to login with external provider basically the Form Authentication causes the issue but how to force the Owin method to pass the Authorization, I added [AllowAnonymous] but didn't solve it.</p>
  
  <p>For Facebook and Google there is a js solution to open the login using there api but for Twitter I didn't find a way to open the login page using Twitter js api, so for this reason I need to get Owin to work since I need the user to login using his Twitter account.</p>
  
  <p>Please Advise</p>