"Address already exists" when creating a new user, but user is created anyway

When creating a new user via the REST API, if the email address exists, it reports "Address already exists", but it creates the user anyway.

After a bit of deep cave diving into the code I suspect it’s this in model/usermanager.py

This function appears to create a user before it checks to see if the address exists, with the result that multiple users are created when the address already exists.

@implementer(IUserManager)
class UserManager:
   """See `IUserManager`."""

   def create_user(self, email=None, display_name=None):
       """See `IUserManager`."""
       user = User(display_name, Preferences())
       if email:
           address = self.create_address(email, display_name)
           user.link(address)
       return user

this seems to fix the problem - but please don’t trust my solution - needs verification.

@implementer(IUserManager)
class UserManager:
   """See `IUserManager`."""

   def create_user(self, email=None, display_name=None):
       """See `IUserManager`."""
       if email:
           address = self.create_address(email, display_name)
       user = User(display_name, Preferences())
       if email:
           user.link(address)
       return user