unlink(nullptr) is UB, so don't do that HTCONDOR-409
unlink(nullptr) is UB, so don't do that HTCONDOR-409

htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor