dom0/core: save real netvm of DispVM

Netvm of DispVM is based on DispVM-template settings. So save the real one
instead of assuming default netvm.

dom0/qvm-core/qubes.py

@@ -2230,6 +2230,7 @@ class QubesDisposableVm(QubesVm):
         attrs["template_qid"] = str(self.template.qid)
         attrs["label"] = self.label.name
         attrs["firewall_conf"] = self.relative_path(self.firewall_conf)
+        attrs["netvm_qid"] = str(self.netvm.qid) if self.netvm is not None else "none"
         return attrs
 
     def verify_files(self):
@@ -2601,11 +2602,11 @@ class QubesVmCollection(dict):
         return vm
 
     def add_new_disposablevm(self, name, template, dispid,
-                      label = None):
+                      label = None, netvm = None):
 
         qid = self.get_new_unused_qid()
         vm = QubesDisposableVm (qid=qid, name=name, template=template,
-                         netvm = self.get_default_netvm(),
+                         netvm = netvm,
                          label=label, dispid=dispid)
 
         if not self.verify_new_vm (vm):

dom0/restore/qfile-daemon-dvm

@@ -88,7 +88,7 @@ class QfileDaemonDvm:
             qvm_collection.unlock_db()
             return None
         dispid=int(disp_name[4:])
-        dispvm=qvm_collection.add_new_disposablevm(disp_name, vm_disptempl.template, label=label, dispid=dispid)
+        dispvm=qvm_collection.add_new_disposablevm(disp_name, vm_disptempl.template, label=label, dispid=dispid, netvm=vm_disptempl.netvm)
         # By default inherit firewall rules from calling VM
         if os.path.exists(vm.firewall_conf):
             disp_firewall_conf = '/var/run/qubes/%s-firewall.xml' % disp_name