PigStats.isSuccessful returns false if embedded pig script has dump

The below is my python script,

#! /usr/bin/python
from  org.apache.pig.scripting import Pig

P = Pig.compileFromFile("""a.pig""")
result = P.bind().runSingle()

if result.isSuccessful():
    print 'Pig job succeeded'
else:
    print 'Pig job failed'

The below is the pig script embedded (a.pig)
A = LOAD 'a1' USING PigStorage(',') AS (f1:chararray,f2:chararray);
B = GROUP A by f1;
dump B;

For this script execution, even though the job is successful the output printed is 'Pig job failed'
This is because result.isSuccessful() is returning false whenever the pig script is having a dump statement.

If i run the pig script alone, then the error code returned is proper.