serve: event stream test failed once on aarch64-darwin in the v0.22.0 release run #201

What

laurel.serve#serve__an_event_stream_lives_while_it_makes_progress failed with exit 13 on the aarch64-darwin leg of the v0.22.0 release run (https://github.com/briar-systems/laurel/actions/runs/36369530127), and passed when that leg was rerun. The same commit passed aarch64-darwin on the integration PR (#200). It is the first failure of this test in the last 40 CI runs.

Repro

Not reproduced. The failing run is the one above, test . --profile debug on aarch64-darwin, laurel at v0.22.0 (http 0.25.0, std 9.3.0).

Expected

The client reads the whole chunked event stream, through the terminating 0\r\n\r\n, and the test passes.

Actual

Exit 13 is client result 3 in event_scenario: a tcp.stream_read returned an error or end of stream before the terminator arrived, or the 1024-byte buffer filled. The scenario sleeps 100 ms per event and reads nothing until all ten are published, under a 300 ms response_timeout_ns. Worth checking against http 0.25's changes to how a server connection closes (#180 there), since 0.22.0 is the first laurel release on it.