backends: Do not sort strings

Closes #305

backend/local/local.go

@@ -7,7 +7,6 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
-	"sort"
 	"sync"
 
 	"github.com/restic/restic/backend"
@@ -253,7 +252,6 @@ func (b *Local) Remove(t backend.Type, name string) error {
 // goroutine is started for this. If the channel done is closed, sending
 // stops.
 func (b *Local) List(t backend.Type, done <-chan struct{}) <-chan string {
-	// TODO: use os.Open() and d.Readdirnames() instead of Glob()
 	var pattern string
 	if t == backend.Data {
 		pattern = filepath.Join(dirname(b.p, t, ""), "*", "*")
@@ -272,8 +270,6 @@ func (b *Local) List(t backend.Type, done <-chan struct{}) <-chan string {
 		matches[i] = filepath.Base(matches[i])
 	}
 
-	sort.Strings(matches)
-
 	go func() {
 		defer close(ch)
 		for _, m := range matches {

backend/mem/mem_backend.go

@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"errors"
 	"io"
-	"sort"
 	"sync"
 
 	"github.com/restic/restic/backend"
@@ -232,8 +231,6 @@ func memList(be *MemoryBackend, t backend.Type, done <-chan struct{}) <-chan str
 		ids = append(ids, entry.Name)
 	}
 
-	sort.Strings(ids)
-
 	debug.Log("MemoryBackend.List", "list %v: %v", t, ids)
 
 	go func() {

backend/sftp/sftp.go

@@ -9,7 +9,6 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
-	"sort"
 	"strings"
 
 	"github.com/juju/errors"
@@ -407,8 +406,6 @@ func (r *SFTP) List(t backend.Type, done <-chan struct{}) <-chan string {
 				dirs = append(dirs, d.Name())
 			}
 
-			sort.Strings(dirs)
-
 			// read files
 			for _, dir := range dirs {
 				entries, err := r.c.ReadDir(Join(basedir, dir))
@@ -421,8 +418,6 @@ func (r *SFTP) List(t backend.Type, done <-chan struct{}) <-chan string {
 					items = append(items, entry.Name())
 				}
 
-				sort.Strings(items)
-
 				for _, file := range items {
 					select {
 					case ch <- file:
@@ -442,8 +437,6 @@ func (r *SFTP) List(t backend.Type, done <-chan struct{}) <-chan string {
 				items = append(items, entry.Name())
 			}
 
-			sort.Strings(items)
-
 			for _, file := range items {
 				select {
 				case ch <- file: