examples/simpleish: 10th thread (random) times out reading response

[klardotsh]

as of 201f133, the 10th (random number, seems to favour 0 but occasionally will be any number 0-9) thread in cargo run --release -- 'http://localhost:7667' examples/simpleish/seatrial.ron times out if ControlFlow(GoTo(..)) has a max_times set (perhaps also if it doesn't, I haven't comprehensively tested yet). unsure yet whether this is an issue with the vial-based server app or with seatrial itself.

[klardotsh]

did some digging on this this afternoon. so far I've ruled out sigaloid's fork of vial being the issue (upstream still repros), and also have confirmed that our call to std::thread::sleep doesn't somehow poison the threadpool or something (removing the sleep still repros the issue)

[klardotsh]

I have at least isolated this to the example server app: running the example sequence against an internal Dockwa app does not repro this issue, but against the example server, repros reliably

[pdpol]

To add a little more color to this issue, my single count grunt here https://github.com/dockwa/seatrial/pull/7/files#diff-21d12a0b73b9779864f16485c0f9e7550a700137c72d490e1c23b46fbdf3d913R5-R9 also hits this timeout, so it may be that 1 thread is guaranteed to hit this issue, may simplify debugging in a multi-threaded context.