Saving map with landscape creates texture asset in content browser

Saving map with landscape creates texture asset in content browser.

1. Download, unzip, open attached project
2. Press File>New Level>Default
3. Go to Modes>Landscape Mode>Create
4. Press Save> Name map "testmap">Save

Results:

new .umap file and new texture file are added to content browser.

Expected:

New .umap file is created in content browser.