reduce parameter missing in CouchbaseViewQuery

The reduce() function is not documented, and when used, ends up throwing a weird error during query time:

$query->limit(5);
$query->reduce(false);
$query->stale(CouchbaseViewQuery::UPDATE_NONE);

Fatal error: Uncaught exception 'CouchbaseException' with message 'query_parse_error: Invalid boolean parameter: []' in CouchbaseNative:873
Stack trace:
#0 CouchbaseNative(917): CouchbaseBucket->_view('_view', 'beer', 'brewery_beers', Array)
#1 /Users/mnunberg/Source/musical-chairs-php/tmp.php(17): CouchbaseBucket->query(Object(_CouchbaseDefaultViewQuery))
#2

thrown in CouchbaseNative on line 873