Read the post; apparently Zend doesn't make deep array copies in some circumstances. The quote from the spec is "Unlike conforming deferred string copy mechani

Read the post; apparently Zend doesn't make deep array copies in some circumstances. The quote from the spec is "Unlike conforming deferred string copy mechanisms discussed in §§ that must produce the same observable behavior as eager string copying, deferred array copy mechanisms are allowed in some cases to exhibit observably different behavior than eager array copying." Note the phrasing "observably different behavior".