Update dependencies (#5518)

vendor/gopkg.in/src-d/go-git.v4/storage/filesystem/dotgit/dotgit.go

@@ -83,7 +83,7 @@ type DotGit struct {
 	packList   []plumbing.Hash
 	packMap    map[plumbing.Hash]struct{}
 
-	files map[string]billy.File
+	files map[plumbing.Hash]billy.File
 }
 
 // New returns a DotGit value ready to be used. The path argument must
@@ -245,8 +245,15 @@ func (d *DotGit) objectPackPath(hash plumbing.Hash, extension string) string {
 }
 
 func (d *DotGit) objectPackOpen(hash plumbing.Hash, extension string) (billy.File, error) {
-	if d.files == nil {
-		d.files = make(map[string]billy.File)
+	if d.options.KeepDescriptors && extension == "pack" {
+		if d.files == nil {
+			d.files = make(map[plumbing.Hash]billy.File)
+		}
+
+		f, ok := d.files[hash]
+		if ok {
+			return f, nil
+		}
 	}
 
 	err := d.hasPack(hash)
@@ -255,11 +262,6 @@ func (d *DotGit) objectPackOpen(hash plumbing.Hash, extension string) (billy.Fil
 	}
 
 	path := d.objectPackPath(hash, extension)
-	f, ok := d.files[path]
-	if ok {
-		return f, nil
-	}
-
 	pack, err := d.fs.Open(path)
 	if err != nil {
 		if os.IsNotExist(err) {
@@ -270,7 +272,7 @@ func (d *DotGit) objectPackOpen(hash plumbing.Hash, extension string) (billy.Fil
 	}
 
 	if d.options.KeepDescriptors && extension == "pack" {
-		d.files[path] = pack
+		d.files[hash] = pack
 	}
 
 	return pack, nil