IndexOutOfBoundsException when adding a Group Build Definitions

When trying to add a Group Build Definitions to a non-empty group containing no default build definion, an IndexOutOfBoundsException exception is thrown.

How to reproduce:

Create a group using a template containing no default Group Build Definition.
Add a project to this group.
Add a Group Build Definition.

Error received:

java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
at java.util.ArrayList.RangeCheck(ArrayList.java:547)
at java.util.ArrayList.get(ArrayList.java:322)
at org.apache.maven.continuum.web.action.BuildDefinitionAction.input(BuildDefinitionAction.java:215)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
....

Full stack trace attached.