BugFix Import access_data

management/commands/import_userdata.py

                                     cnt_all_datasets += 1
                                     try:
                                         item = Item.objects.get(rel_path=rel_path)
-                                    except User.DoesNotExist:
+                                    except Item.DoesNotExist:
                                         cnt_item_missing += 1
                                     else:
                                         if item.public_access:
                                     else:
                                         try:
                                             item = Item.objects.get(rel_path=rel_path)
-                                        except User.DoesNotExist:
+                                        except Item.DoesNotExist:
                                             cnt_item_missing += 1
                                         else:
                                             if user in item.read_access.all():
                                     else:
                                         try:
                                             item = Item.objects.get(rel_path=rel_path)
-                                        except User.DoesNotExist:
+                                        except Item.DoesNotExist:
                                             cnt_item_missing += 1
                                         else:
                                             if user in item.modify_access.all():