Do full email validation in oauth signup form

These fields aren't editable anyway, but if we don't do the full
validation we will instead crash if for example the same account
creation form is submitted twice (happens surprisingly often). Now we
will instead show a validation error message.

Author: mhagander

pgweb/account/forms.py

@@ -28,6 +28,18 @@ def _clean_username(username):
     raise forms.ValidationError("This username is already in use")
 
 
+def _clean_email(email):
+    email = email.lower()
+
+    if User.objects.filter(email=email).exists():
+        raise forms.ValidationError("A user with this email address is already registered")
+
+    if SecondaryEmail.objects.filter(email=email).exists():
+        raise forms.ValidationError("This email address is already attached to a different user")
+
+    return email
+
+
 # Override some error handling only in the default authentication form
 class PgwebAuthenticationForm(AuthenticationForm):
     def clean(self):
@@ -91,15 +103,7 @@ def clean_username(self):
         return _clean_username(self.cleaned_data['username'])
 
     def clean_email(self):
-        email = self.cleaned_data['email'].lower()
-
-        if User.objects.filter(email=email).exists():
-            raise forms.ValidationError("A user with this email address is already registered")
-
-        if SecondaryEmail.objects.filter(email=email).exists():
-            raise forms.ValidationError("This email address is already attached to a different user")
-
-        return email
+        return _clean_email(self.cleaned_data['email'])
 
 
 class SignupOauthForm(forms.Form):
@@ -122,7 +126,7 @@ def clean_username(self):
         return _clean_username(self.cleaned_data['username'])
 
     def clean_email(self):
-        return self.cleaned_data['email'].lower()
+        return _clean_email(self.cleaned_data['email'])
 
 
 class UserProfileForm(forms.ModelForm):