Unsupported method returns no error, may cause misleading success result in grpc call

[chrisxuwq]

core/engine/virt/virt.go

Lines 185 to 189 in c5f33e0

	// VirtualizationCopyTo copies one.
	func (v *Virt) VirtualizationCopyTo(ctx context.Context, ID, target string, content io.Reader, AllowOverwriteDirWithFile, CopyUIDGID bool) (err error) {
	log.Warnf("VirtualizationCopyTo does not implement")
	return
	}

Just use eru-cli to call send cmd line and it shows result is successful, but actually it fails cuz this method did not implement.
Maybe return an error would be better to avoid misleading successful message?

[chrisxuwq]

and also there's other not implemented methods for yavirt