Here is my output from a fresh Ubuntu 14.04.3 x64 (also tried 15.10 x64) Digital Ocean instance. The first line of the second terminal was a successful run (exits properly within milliseconds), the second run will hang indefinitely and not exit. Note that the actual number of times I need to run the client until it will fail is seemingly random.

first terminal

root@ubuntu-2gb-sfo1-01:~# apt-get update && apt-get install -y git curl
<output trimmed>
root@ubuntu-2gb-sfo1-01:~# curl -O https://storage.googleapis.com/golang/go1.5.3.linux-amd64.tar.gz
<output trimmed>
root@ubuntu-2gb-sfo1-01:~# tar -zxf go1.5.3.linux-amd64.tar.gz
root@ubuntu-2gb-sfo1-01:~# mv go /usr/local
root@ubuntu-2gb-sfo1-01:~# export PATH=$PATH:/usr/local/go/bin
root@ubuntu-2gb-sfo1-01:~# mkdir gopath
root@ubuntu-2gb-sfo1-01:~# export GOPATH=/root/gopath
root@ubuntu-2gb-sfo1-01:~# go get github.com/dpetersen/headerbug/client
root@ubuntu-2gb-sfo1-01:~# go get github.com/dpetersen/headerbug/server
root@ubuntu-2gb-sfo1-01:~# $GOPATH/bin/server localhost:4000
2016/01/22 22:11:43 starting server at localhost:4000

second terminal

root@ubuntu-2gb-sfo1-01:~# /root/gopath/bin/client localhost:4000
2016/01/22 22:13:09 connected
2016/01/22 22:13:09 rpc error: code = 12 desc = "unknown service Foo"
root@ubuntu-2gb-sfo1-01:~# /root/gopath/bin/client localhost:4000
2016/01/22 22:13:09 connected