fix for r5114 which was breaking special previewing types by deleting the intermediate hpr jpg

git-svn-id: http://svn.montala.net/svn/resourcespace@5242 c08608d7-6e46-0410-86ca-f2a6f1370df5
FIX - different fix for 5114 using keep_for_hpr variable as intended

git-svn-id: http://svn.montala.net/svn/resourcespace@5243 c08608d7-6e46-0410-86ca-f2a6f1370df5