We calculated the expiry at time of download by looking at Max-Age, but
as long as must-revalidate was true we would just perform the network
request anyway.
One issue this, further, highlights is our PreferNetwork and PreferCache
options having no behavioral differences while being documented to
do different things. They both consult the cache first and returns any
non-stale data from there.
Fixes: QTBUG-128484
Change-Id: I24b62e2bb072446e463482a778da7cfbd82a6835
Reviewed-by: Mate Barany <mate.barany@qt.io>
(cherry picked from commit e4a35df2afc306e566884f3d917daa08e41761f8)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>