Job Hangs - GROUPing a null relation

[Sirchabesan, Kannappan]

Hi
  I am encountering an issue where the pig job just hangs indefinitely. On 
debugging, I find that the issue seems to happen when GROUPing a null relation 
on multiple fields. 

code:
a = LOAD 'emptyfile';
b = GROUP a BY ($0, $1);
DUMP b;

-- Pig 0.8.1 + hadoop 0.20.2

Has anyone encountered this issue ?. Any pointers to a solution or a JIRA 
ticket?. I am relatively new to working with Pig.

Thanks
Kannappan