_api/$metadata or _vti_bin/client.svc/$metadata no longer working in Office365 Preview

Since a couple of days I've noticed that in some Office365 Preview sites OData V3 endpoints e.g. sitename/_api/$metadata or sitename/_vti_bin/client.svc/$metadata doesn't return any longer the MetaData document.

Instead an error is returned:

  <m:error xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata">
    <m:code>-1, Microsoft.SharePoint.Client.ResourceNotFoundException</m:code>
    <m:message xml:lang="en-US">Cannot find resource for the request $metadata.</m:message>  </m:error>

In http://www.odata.org/media/30002/OData.html#metadatarequests it states that

<quote>

OData services MUST expose a Metadata Document which defines all data exposed by the service. TheMetadata Document URL SHOULD be the root URL of the service with “/$metadata” appended. To retrieve this document a client issues a GET request to the Metadata Document URL.

</quote>

Does anybody know if this is only a temporary glitch or if the syntax how to access the metadata changed during some internal upgrade?

Thanks,

Rainer