xs:date timezone problem

[Sorin Marian Nasoi]

test-case "cbcl-hash-join-3" from "prod-WhereClause" is failing after it was updated to become timezone independent.

For details please see https://www.w3.org/Bugs/Public/show_bug.cgi?id=21222

query:
for $x in (xs:date("2010-10-10"), xs:date("1997-01-01+12:00"), xs:date("1997-01-02+12:00")) for $y in (adjust-date-to-timezone(xs:date("2010-10-10"), implicit-timezone()), xs:date("1997-01-01-12:00")) where $x = $y return $x

expected result string
2010-10-10 1997-01-02+12:00

actual result returned by Zorba is string
1997-01-02+12:00