Regarding coroutine cancellation, apparently 1) If...

# coroutines

[Felix]

Regarding coroutine cancellation, apparently
1) If a coroutine is cancelled after termination, then a posterior join or await will succeed without throwing.
2) If a coroutine is cancelled before termination but ignores the cancellation (i.e. the coroutine ends without exception), a posterior join or await will throw.
Is this behaviour documented? Is there a strong rationale for it? Since cancellation needs to be cooperative, I was expecting an ignored cancel to produce no effects. Namely a posterior join or await would return the result and not throw. I may however be biased on how cancellation works on .NET.
Thanks.