cannot download, /home/azhukov/go is a GOROOT, not a GOPATH
问题详情：
go环境安装好后，运行go代码也没有问题
下载govendor包的时候提示：
cannot download, /home/azhukov/go is a GOROOT, not a GOPATH
解决方法：
This error is caused by the go tool detecting a Go installation in your GOPATH. It's not telling you that your GOPATH is the GOROOT (that's a different message), it's telling your GOPATH looks like aGOROOT.
Cleaning out your GOPATH and running go get again will fix the error.
查看GOROOT和GOPATH配置均没有问题，后发现GOPATH文件夹下目录结构和GOROOT一样，不知道何时go在GOPATH下也安装了。
删除GOPATH文件夹下所有文件，重新执行命令，问题解决。
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