Support bazaar checkout and bazaar branch

Config:

[ghq]
    vcs = bazaar

Examples:

$ ghq get https://launchpad.net/terminator
     clone https://launchpad.net/terminator -> /path/to/launchpad.net/terminator
       bzr branch https://launchpad.net/terminator /path/to/launchpad.net/terminator
$ ghq get -u https://launchpad.net/terminator
    update /path/to/launchpad.net/terminator
       bzr pull

local_repository.go

@@ -160,10 +160,17 @@ func (repo *LocalRepository) VCS() *VCSBackend {
 	if err == nil && fi.IsDir() {
 		return cvsDummyBackend
 	}
+
+	fi, err = os.Stat(filepath.Join(repo.FullPath, ".bzr"))
+	if err == nil && fi.IsDir() {
+		return BazaarBackend
+	}
+
+
 	return nil
 }
 
-var vcsDirs = []string{".git", ".svn", ".hg", "_darcs", ".fslckout", "_FOSSIL_", "CVS"}
+var vcsDirs = []string{".git", ".svn", ".hg", "_darcs", ".fslckout", "_FOSSIL_", "CVS", ".bzr"}
 
 func walkLocalRepositories(callback func(*LocalRepository)) error {
 	roots, err := localRepositoryRoots()

logger/log.go

@@ -12,6 +12,7 @@ var logger = colorine.NewLogger(
 		"hg":       colorine.Verbose,
 		"svn":      colorine.Verbose,
 		"darcs":    colorine.Verbose,
+		"bzr"  :    colorine.Verbose,
 		"skip":     colorine.Verbose,
 		"cd":       colorine.Verbose,
 		"resolved": colorine.Verbose,

remote_repository.go

@@ -170,6 +170,10 @@ func (repo *OtherRepository) VCS() (*VCSBackend, *url.URL) {
 		if vcs == "fossil" {
 			return FossilBackend, repo.URL()
 		}
+
+		if vcs == "bazaar" {
+			return BazaarBackend, repo.URL()
+		}
 	}
 
 	// Detect VCS backend automatically

vcs.go

@@ -162,6 +162,22 @@ var FossilBackend = &VCSBackend{
 	},
 }
 
+var BazaarBackend = &VCSBackend{
+	// bazaar seems not supporting shallow clone currently.
+	Clone: func(remote *url.URL, local string, ignoredShallow, silent bool) error {
+		dir, _ := filepath.Split(local)
+		err := os.MkdirAll(dir, 0755)
+		if err != nil {
+			return err
+		}
+
+		return run(silent)("bzr", "branch", remote.String(), local)
+	},
+	Update: func(local string, silent bool) error {
+		return runInDir(silent)(local, "bzr", "pull")
+	},
+}
+
 var vcsRegistry = map[string]*VCSBackend{
 	"git":        GitBackend,
 	"github":     GitBackend,
@@ -172,4 +188,5 @@ var vcsRegistry = map[string]*VCSBackend{
 	"mercurial":  MercurialBackend,
 	"darcs":      DarcsBackend,
 	"fossil":     FossilBackend,
+	"bazaar":     BazaarBackend,
 }

vcs_test.go

@@ -275,3 +275,51 @@ func TestCvsDummyBackend(t *testing.T) {
 
 	Expect(err).To(HaveOccurred())
 }
+
+func TestBazaarBackend(t *testing.T) {
+	RegisterTestingT(t)
+
+	tempDir, err := ioutil.TempDir("", "ghq-test")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	localDir := filepath.Join(tempDir, "repo")
+
+	remoteURL, err := url.Parse("https://example.com/git/repo")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	commands := []*exec.Cmd{}
+	lastCommand := func() *exec.Cmd { return commands[len(commands)-1] }
+	cmdutil.CommandRunner = func(cmd *exec.Cmd) error {
+		commands = append(commands, cmd)
+		return nil
+	}
+
+	err = BazaarBackend.Clone(remoteURL, localDir, false, false)
+
+	Expect(err).NotTo(HaveOccurred())
+	Expect(commands).To(HaveLen(1))
+	Expect(lastCommand().Args).To(Equal([]string{
+		"bzr", "branch", remoteURL.String(), localDir,
+	}))
+
+	err = BazaarBackend.Clone(remoteURL, localDir, true, false)
+
+	Expect(err).NotTo(HaveOccurred())
+	Expect(commands).To(HaveLen(2))
+	Expect(lastCommand().Args).To(Equal([]string{
+		"bzr", "branch", remoteURL.String(), localDir,
+	}))
+
+	err = BazaarBackend.Update(localDir, false)
+
+	Expect(err).NotTo(HaveOccurred())
+	Expect(commands).To(HaveLen(3))
+	Expect(lastCommand().Args).To(Equal([]string{
+		"bzr", "pull",
+	}))
+	Expect(lastCommand().Dir).To(Equal(localDir))
+}