go: crypto/tls: go get failed on Mac with "x509: certificate signed by unknown authority"

Please answer these questions before submitting your issue. Thanks!

What did you do?

If possible, provide a recipe for reproducing the error. A complete runnable program is good. A link on play.golang.org is best. $ go get -d k8s.io/kubernetes
package k8s.io/kubernetes: unrecognized import path “k8s.io/kubernetes” (https fetch: Get https://k8s.io/kubernetes?go-get=1: x509: certificate signed by unknown authority)

What did you expect to see?

Packages can be pulled down and installed directly

What did you see instead?

The x509 certificate error prevents everything

System details

go version go1.10 darwin/amd64
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/phye/Library/Caches/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Volumes/gitws/go"
GORACE=""
GOROOT="/usr/local/Cellar/go/1.10/libexec"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.10/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/ch/0fcsjfy14kd6jgpzwky0ggvm0000gn/T/go-build042818790=/tmp/go-build -gno-record-gcc-switches -fno-common"
GOROOT/bin/go version: go version go1.10 darwin/amd64
GOROOT/bin/go tool compile -V: compile version go1.10
uname -v: Darwin Kernel Version 17.4.0: Sun Dec 17 09:19:54 PST 2017; root:xnu-4570.41.2~1/RELEASE_X86_64
ProductName:	Mac OS X
ProductVersion:	10.13.3
BuildVersion:	17D102
lldb --version: lldb-900.0.64
  Swift-4.0