Check if grpc 1.7 fixes the HTTP_PROXY unix socket bug
A while ago we discovered an issue where if one of the curl http_proxy environment variables was set, the ruby gRPC client in gitlab-ce would try to use the proxy to connect to Gitaly over a Unix socket. This makes no sense, the proxy should be ignored.
We reported this issue back to gRPC and they made a change that should fix it. https://github.com/grpc/grpc/pull/12739
However, we did not get verification that this solves the problem reported by our users. Because we put one RPC in opt-out for 10.2, this can become an issue for users in GitLab 10.2.
We should verify grpc 1.7.2 fixes the proxy issue, and if so update 10-2-stable to use the grpc 1.7.2 client. Note that this is only about the Ruby client.