[ahoge]

Well, "tricked"... sounds more like a silly bug to me. Stuff like this is easy to miss during testing, because you test these things in isolation.

[ineedtosleep]

It's very unlikely that this is a bug.

There is no reason that that a failed form validation would save the states of all the input fields EXCEPT the bundle selector.

[gkoberger]

Radio buttons are more prone to logical errors than normal fields, just due to the way they work. They're not rocket scientist hard, but they're totally "I didn't have enough coffee and screwed up the logic" hard.