A problem with metadata:FilesystemMetadataProvider

[Peter Schober]

* Marco Malavolti <marco.malavolti at garr.it> [2014-08-12 15:59]:
> The "http://www.example.it/metadata/metadata-sha256.xml" has a new
> validUntil value, but the backingFile is not updated.
[...]
> Metadata document from
> 'http://www.example.it/metadata/metadata-sha256.xml' has not changed
> since last retrieval

Those two statements seem to contradict each other. Does the server
hosting the metadata support any of the more advanced methods to
indicate an unchanged resource (Last-Modified, ETag)?
-peter