actual or constructive, is not necessaaril relevant. The question in such cases is whether the payor reasonably expected to get securitt with a priority equal to the mortgage being paid. Ordinarily lenders who provide refinancing desire and expect precisely that, even if they are aware of an intervennin lien. . . . A refinancing mortgagee should be found to lack such an expectation only where there is affirmative proof that the mortgagee intended to subordinate its mortgage to the intervening...