Select does not delete old items when changing stores

[haysmark]

See the attached test case, which is a variation of the Codependent ComboBox? example, but with Selects instead.

When you pick a state, the city drop down should only have cities from the selected state. Instead, the first time you select a state, the cities are appended to the end of the list - the old cities are not deleted.

[haysmark]

Test case

[Douglas Hays]

Duplicate of #17217.