Undo (ctrl-z) import leaves ghost configuration options

[M0ebiu5]

When importing a flow, which contains unknown nodes with a configuration option, the undo operation does not work properly.

It does not revert the configuration option of the unknown nodes - this leads to an error afterwards when deploying.

To reproduce, import a flow containing an unknown node with configuration options. Undo the operation and check config tab for the configuration options of the unknown node.