[ci skip] Merge pull request #4962 from ytetsuro/patch-2

oci8_forge add column bug fix
diff --git a/system/database/drivers/oci8/oci8_forge.php b/system/database/drivers/oci8/oci8_forge.php
index ac33cde..70fc5c4 100644
--- a/system/database/drivers/oci8/oci8_forge.php
+++ b/system/database/drivers/oci8/oci8_forge.php
@@ -126,6 +126,7 @@
 					$sqls[] = $sql.' RENAME COLUMN '.$this->db->escape_identifiers($field[$i]['name'])
 						.' '.$this->db->escape_identifiers($field[$i]['new_name']);
 				}
+				$field[$i] = "\n\t".$field[$i]['_literal'];
 			}
 		}
 
@@ -136,7 +137,7 @@
 
 		// RENAME COLUMN must be executed after MODIFY
 		array_unshift($sqls, $sql);
-		return $sql;
+		return $sqls;
 	}
 
 	// --------------------------------------------------------------------