taxonomy_autocomplete() has changed in D7 - expects a field name and not a vid [#925302]

taxonomy_autocomplete() has changed in D7 in that you can no longer use it with a vocabulary ID like in D6 (e.g. taxonomy/autocomplete/2) since it now expects a taxonomy field name (e.g. taxonomy/autocomplete/field_name). Currently when exposing an taxonomy filter, you can have the option to add autocompletion, but it results in an AJAX error:

An AJAX HTTP error occurred.
HTTP Result Code: 500
Debugging information follows.
Path: taxonomy/autocomplete/1
StatusText: Service unavailable (with message)
ResponseText: PDOException: SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near &#039;)) AND (t.name LIKE &#039;%s%&#039; ESCAPE &#039;\\&#039;) 
LIMIT 10 OFFSET 0&#039; at line 1: SELECT t.tid AS tid, t.name AS name
FROM 
{taxonomy_term_data} t
WHERE  (t.vid IN  ()) AND (t.name LIKE :db_condition_placeholder_0 ESCAPE &#039;\\&#039;) 
LIMIT 10 OFFSET 0; Array
(
[:db_condition_placeholder_0] =&gt; %s%
)
in taxonomy_autocomplete() (line 110 of modules/taxonomy/taxonomy.pages.inc).

I think we may have to provide our own taxonomy auto-completion callback in views that works via vocabulary ID.