In the particular case of the `Portal.open_context().__aexit__()` frame,
due to usage of `contextlib.asynccontextmanager`, we can't easily hook
into monkeypatching a `__tracebackhide__` set nor catch-n-reraise around
the block exit without defining our own `.__aexit__()` impl. Thus, it's
prolly most sane to do something with an override of
`contextlib._AsyncGeneratorContextManager` or the public exposed
`AsyncContextDecorator` (which uses the former internally right?).
Also fixup some old `._invoke` mod paths in comments and just show
`str(eoc)` in `.open_stream().__aexit__()` terminated-by-EoC log msg
since the `repr()` form won't pprint the IPC msg nicely..
f87f5247a1