QTemporaryFile is not designed to promote temporary files
to non-temporary files. So, it, quite importantly, does not
care if the content of the files are flushed to disk before
renaming it into its 'final' destination. This is what
QSaveFile is for.
This was much more time-consuming than intended since I had to debug
this quirk about calling size().
Pick-to: 6.5 6.4 6.2
Fixes: QTBUG-111397
Change-Id: I15b300f6a5748ad3a0be983545ea621269a12ecd
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
e5f295c8a4