Fix up reading of saved log files
Fix up reading of saved log files

Make sure we compensate for sizeof(int) and the stuff we have already
read.

Fixes: #848

wikimedia/operations-debs-varnish,ssm/pkg-varnish,wikimedia/operations-debs-varnish,ssm/pkg-varnish,ssm/pkg-varnish,wikimedia/operations-debs-varnish,wikimedia/operations-debs-varnish,wikimedia/operations-debs-varnish,ssm/pkg-varnish,ssm/pkg-varnish