fail spending allocations received with an opret+tapret transfer

[zoedberg]

Trying to spend the allocations received with a transfer that spent opret and tapret at the same time, the transfer fails with this error:

called `Result::unwrap()` on an `Err` value: Composition(Stock("the invoice requirements can't be fulfilled using available assets or smart contract state."))

This can be seen using this branch and running the tapret_wlt_receiving_opret test.