skip over nonexisting paths

backup.py

@@ -306,6 +306,7 @@ class Backup(object):
                                                   repo['name'],
                                                   self.args['archive']))
                 for p in repo['path']:
+                    if os.path.exists(p):
                         _cmd.append(p)
                 self.logger.debug('VARS: {0}'.format(vars()))
                 # We don't use self.cmdExec() here because we want to explicitly