/usr/share/gocode/src/github.com/fsouza/go-dockerclient/external/github.com/docker/docker/opts/hosts_unix.go is in golang-github-fsouza-go-dockerclient-dev 0.0+git20150905-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 | // +build !windows
package opts
import "fmt"
var DefaultHost = fmt.Sprintf("unix://%s", DefaultUnixSocket)
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