Issues with duplicate outputs in integration tests

[Techcable]

I have run into issues when there are duplicate inputs across two integration tests.

Two of my integration tests have the same derive input:

#[derive(IntegerId, Copy, Clone, Debug, Eq, PartialEq)]
struct ExampleWrapper(u16);

One of these derives is ignored, causing the corresponding test to fail compilation. Presumably this is due to the log line "expander already in progress of writing identical content to [...] by a different crate"

To reproduce this, checkout DuckLogic/intid.rs at commit e765e8d and run cargo test --features intid-derive/_internal-use-expander. The tests in question are idmap/tests/direct.rs and idmap/tests/set.rs.

Make sure you checkout the right commit, as I later added a workaround by appending a random number to Expander::new.