bug 740605: Balrog db.py attempts to commit even if there has been a rollback. r=nthomas, edransch
bug 740605: Balrog db.py attempts to commit even if there has been a rollback. r=nthomas, edransch

mozbhearsum/balrog,testbhearsum/balrog,aksareen/balrog,nurav/balrog,mozbhearsum/balrog,testbhearsum/balrog,mozbhearsum/balrog,tieu/balrog,testbhearsum/balrog,nurav/balrog,testbhearsum/balrog,tieu/balrog,aksareen/balrog,tieu/balrog,aksareen/balrog,mozbhearsum/balrog,aksareen/balrog,nurav/balrog,tieu/balrog,nurav/balrog