Fix ACL grants storage logic

weed/server/filer_server_handlers_write_autochunk.go

@@ -571,7 +571,7 @@ func SaveAmzMetaData(r *http.Request, existing map[string][]byte, isReplace bool
 
 	//acp-grants
 	acpGrants := r.Header.Get(s3_constants.ExtAmzAclKey)
-	if len(acpOwner) > 0 {
+	if len(acpGrants) > 0 {
 		metadata[s3_constants.ExtAmzAclKey] = []byte(acpGrants)
 	}