golang "go get comand" how this works?

Initially I thought it works as like java maven
where it has its own repository and downloads dependencies

but go git seems to have dependency with git Bazaar like version control system.

go get launchpad.net/mgo 
go: missing Bazaar command. See http://golang.org/s/gogetcmd
package launchpad.net/mgo: exec: "bzr": executable file not found in $PATH

Edit:
My main problem is when i do

go get gopkg.in/mgo.v2 I get

fatal: unable to access 'https://gopkg.in/mgo.v2/': SSL certificate problem: self signed certificate in certificate chain
package gopkg.in/mgo.v2: exit status 128

This is because of git needs certificate. I am able to clone this repo using
git -c http.sslVerify=false clone

I have to do the similar setting some where to get it from go get command

My main problem is when I do:

go get gopkg.in/mgo.v2

fatal: unable to access 'https://gopkg.in/mgo.v2/': 
SSL certificate problem: self signed certificate in certificate chain
package gopkg.in/mgo.v2: exit status 128

If the underlying repo is a Git repo (which seems to be the case here: github.com/go-mgo/mgo/tree/v2), then you can deactivate ssl (temporarily) with:

git config --global http.sslVerify false

Initial answer:

As mentioned in go remote import path, some pre-defined import path will require some associated version control tool to be present:

Launchpad (Bazaar)

import "launchpad.net/project"

Go can get from any repo you want, but, as explained in "Structure for your go workspace when using private git repository"

> import paths may either be qualified with the version control type, or the go tool can dynamically fetch the import path over https/http and discover where the code resides from a tag in the HTML.

Here, the import path is enough for go to infer what tool it needs.