grpc-go: Upgrading from 1.7.2 to 1.10.0 causes connections to hang

Please answer these questions before submitting your issue.

What version of gRPC are you using?

Was using 1.7.2 and now using 1.10.0

What version of Go are you using (go version)?

1.10

What operating system (Linux, Windows, …) and version?

Confirmed on Ubuntu 16.04, 17.10 and Amazon Linux.

What did you do?

We upgraded from 1.7.2 to 1.10 grpc package (see https://github.com/containerd/containerd/pull/2186). The code connects with the following https://github.com/containerd/containerd/blob/master/client.go#L71. This is typically over a unix socket.

Details are here: https://github.com/containerd/containerd/issues/2185.

What did you expect to see?

It should not hang.

What did you see instead?

It hangs until there is a timeout. Here is the user experience with a containerd client:

~/g/s/g/c/containerd ❯❯❯ sudo ctr images pull docker.io/library/wordpress:latest                                                                                                                                                                                                                                   master ✭ ◼
ctr: failed to dial "/run/containerd/containerd.sock": context deadline exceeded