Autocomplete tags style is broken for multiple values

Update: In Drupal.jsAC.prototype.select() $(node).data('autocompleteValue') is always a single value.

The problem is that Taxonomy term returns the matches only for the last entered tag

Object {t2, t1: "t1"} (e.g. t2 term was entered before).

ER currently omits previous terms entered.

So it seems that for Tags style, we would need to use something similar to TermAutocompleteController::autocomplete().