Unable to add a shortanswer question with an answer of 0

While testing MDL-29018 I discovered that it was impossible to create question answers with a value of 0.
When I clicked to create a question it would simply not create the question answer in the table. This would in turn allow me to create questions without answers which would horribly break the lesson module.
This is a pretty serious issue as you can kill the lesson module by attempting to create a question where the answer (correct or not) is 0.

Cheers
Sam