The delta was clearly intended to be used on the total (and still is)
but it also wound up getting stored in the cache, which wouldn't be a
big problem unless the object was removed, in which case we could
incidentally 'free up more space' than intended.
Pick-to: 6.0
Change-Id: Ib2b0f072d30da6d16a93dce60e4c5f6080c109fc
Reviewed-by: Lars Knoll <lars.knoll@qt.io>