4.x: Fix accidental behavior change with Task-based Create methods completing when the body ends

[akarnokd]

Before the accidental change, Observable.Create(Func<IObserver<T>,[...], Task<IDisposable>) and Observable.Create(Func<IObserver<T>,[...], Task<Action>) did not complete when the task body ended, unlike Observable.Create(Func<IObserver<T>,[...],Task).

There was an oversight when these operators have been upgraded and the plain Task version's logic was copy-pasted to them. Note though that there were no unit tests verifying the expected behavior at the time.

Fixes: #815

[danielcweber]

@onovotny I think this PR justifies a 4.1.1 or 4.2.0 release.

[clairernovotny]

Okay, anything else that should go into it?

[akarnokd]

I'd say 4.1.1 as this is a patch-level change.

#806, #807 and #809 perhaps?

[clairernovotny]

Okay -- my suggestion would be to create a PR to the rel/v4.1 branch that cherry-picks the changes you want in it. We can then release that. In the PR, it can bump the version.json to 4.1.1. The changes should prob include the latest azure-pipelines.*.yml too.

[danielcweber]

#809 adds a attributes to publicly visible classes and should bump to 4.2.0 then AFAIK. If we definitely want that one in too, we could keep it simple and just release 4.2.0 from master.

[clairernovotny]

I don't think adding attributes is considered a breaking change, especially since it does not affect runtime behavior. Removing, perhaps.

[danielcweber]

Ok. I can prepare the PR later.