Error when trying to register with an email address that is already used

[cdriehuys]

Bug Report

Expected Behavior

When signing up with an email address that has already been used, I expect to get an error stating that the email has been used.

Actual Behavior

A 500 server error occurs with the following traceback:

IntegrityError: duplicate key value violates unique constraint "account_user_email_key"
DETAIL:  Key (email)=(chathan@knowmetools.com) already exists.

  File "django/db/backends/utils.py", line 65, in execute
    return self.cursor.execute(sql, params)
IntegrityError: duplicate key value violates unique constraint "account_user_email_key"
DETAIL:  Key (email)=(chathan@knowmetools.com) already exists.

  File "django/core/handlers/exception.py", line 41, in inner
    response = get_response(request)
  File "django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "django/views/decorators/csrf.py", line 58, in wrapped_view
    return view_func(*args, **kwargs)
  File "django/views/generic/base.py", line 68, in view
    return self.dispatch(request, *args, **kwargs)
  File "rest_framework/views.py", line 489, in dispatch
    response = self.handle_exception(exc)
  File "rest_framework/views.py", line 449, in handle_exception
    self.raise_uncaught_exception(exc)
  File "rest_framework/views.py", line 486, in dispatch
    response = handler(request, *args, **kwargs)
  File "rest_framework/generics.py", line 192, in post
    return self.create(request, *args, **kwargs)
  File "rest_framework/mixins.py", line 21, in create
    self.perform_create(serializer)
  File "rest_framework/mixins.py", line 26, in perform_create
    serializer.save()
  File "rest_framework/serializers.py", line 215, in save
    self.instance = self.create(validated_data)
  File "km_auth/serializers.py", line 133, in create
    user = User.objects.create_user(**validated_data)
  File "account/managers.py", line 150, in create_user
    user.save()
  File "django/contrib/auth/base_user.py", line 80, in save
    super(AbstractBaseUser, self).save(*args, **kwargs)
  File "django/db/models/base.py", line 807, in save
    force_update=force_update, update_fields=update_fields)
  File "django/db/models/base.py", line 837, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "django/db/models/base.py", line 923, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "django/db/models/base.py", line 962, in _do_insert
    using=using, raw=raw)
  File "django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "django/db/models/query.py", line 1076, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "django/db/models/sql/compiler.py", line 1099, in execute_sql
    cursor.execute(sql, params)
  File "raven/contrib/django/client.py", line 114, in execute
    return real_execute(self, sql, params)
  File "django/db/backends/utils.py", line 65, in execute
    return self.cursor.execute(sql, params)
  File "django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "django/db/backends/utils.py", line 65, in execute
    return self.cursor.execute(sql, params)

[cdriehuys]

I believe the root cause of this is that we have been assuming email addresses will be unique. We are now seeing that this is true only for verified email addresses.