Arvados

In #22184 we added a UUID-to-PDH lookup in each request. If the session cache doesn't match the current PDH, we Sync the cache before processing the request. In a series of PUT requests, this adds a Sync to every request.

It would be better to avoid the extra Sync by updating the session cache with the new file content after the webdav PUT handler succeeds. Most of the time, the PDH returned by the PATCH request will agree with the UUID-to-PDH lookup in the next request, and the extra Sync will be skipped.