Added CloseDBConnection() to replace the old CloseReaderCommand(). This will close the MySQLConnection attached to a MySQLCommand. I'm not sure if this accounts for every time a database connection needs to be closed, but it matches up 1:1 with the places where the database connection was previously being closed

OpenSim/Data/MySQL/MySQLAuthenticationData.cs

@@ -82,12 +82,16 @@ namespace OpenSim.Data.MySQL
                             ret.Data[s] = result[s].ToString();
                         }
 
+                        CloseDBConnection(cmd);
                         return ret;
                     }
+                    else
+                    {
+                        CloseDBConnection(cmd);
+                        return null;
+                    }
                 }
             }
-
-            return null;
         }
 
         public bool Store(AuthenticationData data)