iOS: cannot drag feed into an empty folder

[glfmn]

Dragging feeds between folders moves them to a new folder as expected. However, if the folder is empty (such as when newly created), the app will fail to move the feed to the new folder until a feed is added manually.

When I first downloaded the app, I thought dragging feeds between folders was not implemented for this reason. I had to delete and recreate feeds to get the desired effect.