It's a problem to use one route for the form and one route for the
submission of the form. When user is not logged and he tries to submit
with an existing email, a error tell him to sign in before submitting.
To login in there is a button that let him sign in. But after loggin in,
he comes back to the post url of the form and this url doesn't perform
checks that are performed when arriving on the form for the first time.
Rémy Taymans
e053dff6d2