@mriehm, thank you for this. Can you add a similar check in the ReadAsync method too?

/azp run

Sure. Done.

ReadAsync() appears to be just a wrapper for Read(), so I don't know if adding the check to ReadAsync() itself is behaviorally required, but it may be a performance optimization.

/azp run

@mriehm, the async read does an async pre-read before synchronously reading. This is because the read goes through a serializer which is sync only. The pre-read is to make and effort to fill a buffer hoping it's enough and can be done asynchronously. It's a best effort attempt to try and get things to actually happen async.
I'll merge this as soon as the tests pass. The failure was nothing to do with your change.

Test which is failing is due to needing an updated version of the testserver being deployed and this PR is based off an older commit. This should be safe to merge so merging despite test failures.