Test failure in `http2_connect_detect_close`

[Darksonn]

The following spurious test failure has been observed in Tokio's CI setup:

failures:

---- conn::http2_connect_detect_close stdout ----

thread 'conn::http2_connect_detect_close' panicked at tests\client.rs:2377:14:
drop with 1s: Elapsed(())
stack backtrace:
   0: std::panicking::begin_panic_handler
             at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library\std\src\panicking.rs:697
   1: core::panicking::panic_fmt
             at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library\core\src\panicking.rs:75
   2: core::result::unwrap_failed
             at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library\core\src\result.rs:1704
   3: enum2$<core::result::Result<enum2$<core::result::Result<tuple$<>,futures_channel::oneshot::Canceled> >,tokio::time::error::Elapsed> >::expect<enum2$<core::result::Result<tuple$<>,futures_channel::oneshot::Canceled> >,tokio::time::error::Elapsed>
             at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359\library\core\src\result.rs:1061
   4: client::conn::http2_connect_detect_close::async_block$0
             at .\tests\client.rs:2375
   5: core::future::future::impl$1::poll<ref_mut$<dyn$<core::future::future::Future<assoc$<Output,tuple$<> > > > > >
             at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359\library\core\src\future\future.rs:124
   6: tokio::runtime::park::impl$4::block_on::closure$0<core::pin::Pin<ref_mut$<dyn$<core::future::future::Future<assoc$<Output,tuple$<> > > > > > >
             at D:\a\tokio\tokio\tokio\src\runtime\park.rs:285
   7: tokio::task::coop::with_budget
             at D:\a\tokio\tokio\tokio\src\task\coop\mod.rs:167
   8: tokio::task::coop::budget
             at D:\a\tokio\tokio\tokio\src\task\coop\mod.rs:133
   9: tokio::runtime::park::CachedParkThread::block_on<core::pin::Pin<ref_mut$<dyn$<core::future::future::Future<assoc$<Output,tuple$<> > > > > > >
             at D:\a\tokio\tokio\tokio\src\runtime\park.rs:285
  10: tokio::runtime::context::blocking::BlockingRegionGuard::block_on<core::pin::Pin<ref_mut$<dyn$<core::future::future::Future<assoc$<Output,tuple$<> > > > > > >
             at D:\a\tokio\tokio\tokio\src\runtime\context\blocking.rs:66
  11: tokio::runtime::scheduler::multi_thread::impl$0::block_on::closure$0<core::pin::Pin<ref_mut$<dyn$<core::future::future::Future<assoc$<Output,tuple$<> > > > > > >
             at D:\a\tokio\tokio\tokio\src\runtime\scheduler\multi_thread\mod.rs:87
  12: tokio::runtime::context::runtime::enter_runtime<tokio::runtime::scheduler::multi_thread::impl$0::block_on::closure_env$0<core::pin::Pin<ref_mut$<dyn$<core::future::future::Future<assoc$<Output,tuple$<> > > > > > >,tuple$<> >
             at D:\a\tokio\tokio\tokio\src\runtime\context\runtime.rs:65
  13: tokio::runtime::scheduler::multi_thread::MultiThread::block_on<core::pin::Pin<ref_mut$<dyn$<core::future::future::Future<assoc$<Output,tuple$<> > > > > > >
             at D:\a\tokio\tokio\tokio\src\runtime\scheduler\multi_thread\mod.rs:86
  14: tokio::runtime::runtime::Runtime::block_on_inner<core::pin::Pin<ref_mut$<dyn$<core::future::future::Future<assoc$<Output,tuple$<> > > > > > >
             at D:\a\tokio\tokio\tokio\src\runtime\runtime.rs:358
  15: tokio::runtime::runtime::Runtime::block_on<core::pin::Pin<ref_mut$<dyn$<core::future::future::Future<assoc$<Output,tuple$<> > > > > > >
             at D:\a\tokio\tokio\tokio\src\runtime\runtime.rs:330
  16: client::conn::http2_connect_detect_close
             at .\tests\client.rs:2375
  17: client::conn::http2_connect_detect_close::closure$0
             at .\tests\client.rs:2306
  18: core::ops::function::FnOnce::call_once<client::conn::http2_connect_detect_close::closure_env$0,tuple$<> >
             at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359\library\core\src\ops\function.rs:250
  19: core::ops::function::FnOnce::call_once
             at /rustc/17067e9ac6d7ecb70e50f92c1944e545188d2359/library\core\src\ops\function.rs:250
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.


failures:
    conn::http2_connect_detect_close

test result: FAILED. 58 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in 5.25s

https://github.com/tokio-rs/tokio/actions/runs/15299588060/job/43036753531

[Darksonn]

CI job passed when re-run.

[seanmonstar]

Hm, relying on TCP close behavior in tests seems to sometimes be flaky... Might be better if we rewrote that test using tokio_test::io...