title: Django- how to use built-in login view with email instead of username?
body: <p>I am using built-in login in my app. There is some custom backends or packages to handle this. but many of them are not what i am looking.</p>
  
  <p>i made email unique via django-registration while registering. now all i want is to ask email in login page instead of username.</p>
  
  <p>but if i use some custom backends like <a href="https://github.com/dabapps/django-email-as-username" rel="noreferrer">django email as username</a> it crashes when using with django-registration.</p>
  
  <p>i dont want to change all authentication backend , i just want to change login page.</p>
  
  <p>in the rest of site ,  i am gonna use username. p.e in my custom admin page when i write:</p>
  
  <pre><code>welcome {{user}}
  </code></pre>
  
  <p>it must render username. not e-mail. </p>
  
  <p>i need to find the way out from this. i am stuck.</p>
  
  <p>thank you.</p>