Prevent corruption of VM in VirtualBox when using linked clone

Fix https://github.com/GNS3/gns3-gui/issues/1821

gns3server/compute/virtualbox/__init__.py

@@ -161,7 +161,7 @@ class VirtualBox(BaseManager):
                 continue
 
     @asyncio.coroutine
-    def list_vms(self):
+    def list_vms(self, allow_clone=False):
         """
         Gets VirtualBox VM list.
         """
@@ -176,7 +176,7 @@ class VirtualBox(BaseManager):
             if vmname == "<inaccessible>":
                 continue  # ignore inaccessible VMs
             extra_data = yield from self.execute("getextradata", [vmname, "GNS3/Clone"])
-            if len(extra_data) == 0 or not extra_data[0].strip() == "Value: yes":
+            if allow_clone or len(extra_data) == 0 or not extra_data[0].strip() == "Value: yes":
                 # get the amount of RAM
                 info_results = yield from self.execute("showvminfo", [vmname, "--machinereadable"])
                 ram = 0

gns3server/compute/virtualbox/virtualbox_vm.py

@@ -603,9 +603,16 @@ class VirtualBoxVM(BaseNode):
         :param vmname: VirtualBox VM name
         """
 
+        if vmname == self._vmname:
+            return
+
         if self.linked_clone:
             if self.status == "started":
                 raise VirtualBoxError("You can't change the name of running VM {}".format(self._name))
+            # We can't rename a VM to name that already exists
+            vms = yield from self.manager.list_vms(allow_clone=True)
+            if vmname in [vm["vmname"] for vm in vms]:
+                raise VirtualBoxError("You can't change the name to {} it's already use in VirtualBox".format(vmname))
             yield from self._modify_vm('--name "{}"'.format(vmname))
 
         log.info("VirtualBox VM '{name}' [{id}] has set the VM name to '{vmname}'".format(name=self.name, id=self.id, vmname=vmname))