Fix handling of AutoSubgroups in readDescriptionFile.

We used to test AutoSubgroups before upgrading the description,
which would break handling of the (obsolete) AllowSubgroups
field.

Thanks to David Saulpic.

group/description.go

@@ -441,6 +441,15 @@ func readDescription(name string, allowSubgroups bool) (*Description, error) {
 	if err != nil {
 		return nil, err
 	}
+	err = upgradeDescription(&desc)
+	if err != nil {
+		return nil, err
+	}
+
+	desc.FileName = fileName
+	desc.fileSize = fi.Size()
+	desc.modTime = fi.ModTime()
+
 	if isSubgroup {
 		if !desc.AutoSubgroups {
 			return nil, os.ErrNotExist
@@ -450,15 +459,6 @@ func readDescription(name string, allowSubgroups bool) (*Description, error) {
 		desc.Description = ""
 	}
 
-	desc.FileName = fileName
-	desc.fileSize = fi.Size()
-	desc.modTime = fi.ModTime()
-
-	err = upgradeDescription(&desc)
-	if err != nil {
-		return nil, err
-	}
-
 	return &desc, nil
 }