Relationship wrong when skipping "Update" button

Imagine the following situation:

A user adds a field, or a filter, or whatever, to the view. But she doesn't click the "Update" button in the following form.

Usually, skipping "Update" isn't harmful: the field handler knows to initialize the options to their defaults when it runs.

However, in one case skipping "Update" is harmful: when the "Relationship" dropdown shows anything but the "none" relationship. In this case, neglecting to click "Update" doesn't configure the field to use the relationship the form seems to say that it uses.

The screenshot demonstrates this scenario:

The user has just added the "Flags: Flag link". Views shows "flag" in the relationship dropdown. However, unless the user clicks "Update", this field isn't really connected to that "flag" relationship.

The patch solves the problem by saving the 'relationship' option immediately when the form is shown (but only when needed).