Delete vlan.dat for L2IOL during config import. Fixes #1285.

gns3server/modules/iou/iou_vm.py

@@ -1064,6 +1064,14 @@ class IOUVM(BaseVM):
                 else:
                     startup_config = startup_config.replace("%h", self._name)
                     f.write(startup_config)
+
+            vlan_file = os.path.join(self.working_dir, "vlan.dat-{:05d}".format(self.application_id))
+            if os.path.exists(vlan_file):
+                try:
+                    os.remove(vlan_file)
+                except OSError as e:
+                    log.error("Could not delete VLAN file '{}': {}".format(vlan_file, e))
+
         except OSError as e:
             raise IOUError("Can't write startup-config file '{}': {}".format(startup_config_path, e))