Fix a Form_validation bug that unnecessarily modifes $_POST
diff --git a/system/libraries/Form_validation.php b/system/libraries/Form_validation.php
index ed4b9bc..e4a5189 100644
--- a/system/libraries/Form_validation.php
+++ b/system/libraries/Form_validation.php
@@ -486,7 +486,7 @@
 		}
 
 		// Now we need to re-set the POST data with the new, processed data
-		$this->_reset_post_array();
+		empty($this->validation_data) && $this->_reset_post_array();
 
 		return ($total_errors === 0);
 	}