Connection pool returns connections which are not ready

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I am running a high number of concurrent requests (~1000) to the AWS Kinesis service and I am getting an error log from the hyper connection pool:

root@doit-1800981089-sz6zt:~/kinesis-hyper-bug# cargo build --release && RUST_LOG=error RUST_BACKTRACE=full ./target/release/kinesis-hyper-bug
    Finished release [optimized + debuginfo] target(s) in 0.0 secs
ERROR 2018-01-31T17:10:32Z: hyper::client: pooled connection was not ready, this is a hyper bug
ERROR 2018-01-31T17:11:49Z: hyper::client: pooled connection was not ready, this is a hyper bug
ERROR 2018-01-31T17:15:16Z: hyper::client: pooled connection was not ready, this is a hyper bug
ERROR 2018-01-31T17:15:58Z: hyper::client: pooled connection was not ready, this is a hyper bug
ERROR 2018-01-31T17:16:00Z: hyper::client: pooled connection was not ready, this is a hyper bug