`http2::handshake()` is useless in 1.0 given no default executor

[conradludgate]

Version

hyper 1.0.0-rc2

Description

hyper::client::conn::http2::handshake(io).await causes an instant panic. Internally it performs Builder::new().handshake(io).await which uses the Exec::Default executor. There is no longer a default tokio runtime implied since the removal of the runtime feature.

https://github.com/hyperium/hyper/blob/master/src/common/exec.rs#L36-L38

There is a TODO in this file to refactor executors. But I couldn't find a relevant issue, so I wanted to open one to ensure this doesn't get included in the official release

[seanmonstar]

Good catch, thank you!