bolthelper.go
func (tx Tx) CopyFile(path string, mode os.FileMode) error {
	return errorsp.WithStacks(tx.Tx.CopyFile(path, mode))
}
func (tx Tx) CopyFile(path string, mode os.FileMode) error {
	return errorsp.WithStacks(tx.Tx.CopyFile(path, mode))
}
// CopyFile copies the entire database to file at the given path. A reader
// transaction is maintained during the copy so it is safe to continue
// using the database while a copy is in progress.