queue: fix logging of child return code
queue: fix logging of child return code

zhouyuan/teuthology,zhouyuan/teuthology,caibo2014/teuthology,robbat2/teuthology,ivotron/teuthology,t-miyamae/teuthology,robbat2/teuthology,michaelsevilla/teuthology,tchaikov/teuthology,SUSE/teuthology,SUSE/teuthology,yghannam/teuthology,caibo2014/teuthology,dreamhost/teuthology,michaelsevilla/teuthology,t-miyamae/teuthology,tchaikov/teuthology,ivotron/teuthology,dmick/teuthology,dreamhost/teuthology,ceph/teuthology,dmick/teuthology,ceph/teuthology,ktdreyer/teuthology,ktdreyer/teuthology,dmick/teuthology,SUSE/teuthology,yghannam/teuthology