go get golang.org/x/tools/cmd/oracle failed in v1.6.3

Please answer these questions before submitting your issue. Thanks!

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

go version go1.6.3 linux/amd64

What operating system and processor architecture are you using (go env)?

CentOS Linux release 7.1.1503 (Core)

[root@nc go]# go env
GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/root/go"
GORACE=""
GOROOT="/usr/lib/golang"
GOTOOLDIR="/usr/lib/golang/pkg/tool/linux_amd64"
GO15VENDOREXPERIMENT="1"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0"
CXX="g++"
CGO_ENABLED="1"
[root@nc go]# go version
go version go1.6.3 linux/amd64

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.

I am getting golang.org/x/tools/cmd/oracle but failed.

What did you expect to see?

I'd like to get and build golang.org/x/tools/cmd/oracle.

What did you see instead?

[root@nc go]# go get golang.org/x/tools/cmd/oracle
package golang.org/x/tools/cmd/oracle: cannot find package "golang.org/x/tools/cmd/oracle" in any of:
        /usr/lib/golang/src/golang.org/x/tools/cmd/oracle (from $GOROOT)
        /root/go/src/golang.org/x/tools/cmd/oracle (from $GOPATH)
[root@nc go]#
[root@nc go]# go get -u -v golang.org/x/tools/cmd/oracle
Fetching https://golang.org/x/tools/cmd/oracle?go-get=1
Parsing meta tags from https://golang.org/x/tools/cmd/oracle?go-get=1 (status code 200)
get "golang.org/x/tools/cmd/oracle": found meta tag main.metaImport{Prefix:"golang.org/x/tools", VCS:"git", RepoRoot:"https://go.googlesource.com/tools"} at https://golang.org/
x/tools/cmd/oracle?go-get=1
get "golang.org/x/tools/cmd/oracle": verifying non-authoritative meta tag
Fetching https://golang.org/x/tools?go-get=1
Parsing meta tags from https://golang.org/x/tools?go-get=1 (status code 200)
golang.org/x/tools (download)
package golang.org/x/tools/cmd/oracle: cannot find package "golang.org/x/tools/cmd/oracle" in any of:
        /usr/lib/golang/src/golang.org/x/tools/cmd/oracle (from $GOROOT)
        /root/go/src/golang.org/x/tools/cmd/oracle (from $GOPATH)