local, yandex, dropbox: fix NewObject suceeding on a directory #1079

Add tests to make it consistent across all remotes

local/local.go

@@ -162,6 +162,9 @@ func (f *Fs) newObjectWithInfo(remote string, info os.FileInfo) (fs.Object, erro
 			return nil, err
 		}
 	}
+	if !o.info.Mode().IsRegular() {
+		return nil, errors.Wrapf(fs.ErrorNotAFile, "%q", remote)
+	}
 	return o, nil
 }