(Coverity)  Make it impossible to strdup() NULL.
(Coverity)  Make it impossible to strdup() NULL.

htcondor/htcondor,htcondor/htcondor,djw8605/htcondor,neurodebian/htcondor,zhangzhehust/htcondor,djw8605/htcondor,zhangzhehust/htcondor,neurodebian/htcondor,djw8605/htcondor,htcondor/htcondor,zhangzhehust/htcondor,zhangzhehust/htcondor,zhangzhehust/htcondor,djw8605/htcondor,htcondor/htcondor,zhangzhehust/htcondor,neurodebian/htcondor,neurodebian/htcondor,zhangzhehust/htcondor,htcondor/htcondor,djw8605/htcondor,htcondor/htcondor,neurodebian/htcondor,neurodebian/htcondor,djw8605/htcondor,htcondor/htcondor,zhangzhehust/htcondor,zhangzhehust/htcondor,neurodebian/htcondor,djw8605/htcondor,djw8605/htcondor,htcondor/htcondor,neurodebian/htcondor,djw8605/htcondor,neurodebian/htcondor