Trying to replicate cases where errors are raised in both `trio` and
`asyncio` tasks independently (at least in `.to_asyncio` API terms) with
a new `test_trio_prestarted_task_bubbles` that generates 3 cases inside
a `@acm` calls stack composing a `trio.Nursery` with
a `to_asyncio.open_channel_from()` call where a set of `trio` tasks are
started in a loop using `.start()` with various exc raising sequences,
- the aio task raising *before* the last `trio` task spawns.
- the aio task raising just after the last trio task spawns, but before
it starts.
- after the last trio task `.start()` call returns control to the
parent - but (for now) did not error.
TODO, still more cases to discover as i'm still fighting a `modden` bug
of this sort atm..
Other,
- tweak some other tests to have timeouts since some recent hangs were
found..
- started mucking with py3.13 and thus adjustments for strict egs in
some tests; full patchset to test suite likely coming soon!
924eff2985