Fix bug introduced by in rev 1.137 "Silence some output when quiet mode is on".  Only silence final output of error if $xmlout is not set as the xmlrpc server depends on this output, but also sets $quiet.
Fix bug introduced by in rev 1.137 "Silence some output when quiet
mode is on".  Only silence final output of error if $xmlout is not set
as the xmlrpc server depends on this output, but also sets $quiet.

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome