Can't add missing image if map exported with only background image and no icons

Exporting map with only background image, XML is created without "images" tag. Adding at least one element to map, "images" tag in XML will hold both images - icon and background.
Having a map with only background results in several unwanted behaviours. In latest version (trunk, for example) import halts with an exception, displaying error about missing background. But importing earlier version XML (for example 1.8), map is created or updated, but image is not and will display error about missing background.
So checkbox for Images (assuming user is Super Admin) "Add missing" doesn't play any role when map is being imported with only background.