fullTableName needs to check for empty schemaName

lib/Cake/Model/Datasource/DataSource.php

@@ -413,7 +413,7 @@ class DataSource extends Object {
  * @access public
  */
 	public function getSchemaName() {
-		return false;
+		return null;
 	}
 
 /**

lib/Cake/Model/Datasource/DboSource.php

@@ -930,14 +930,14 @@ class DboSource extends DataSource {
 		}
 
 		if ($quote) {
-			if ($schema && isset($schemaName)) {
+			if ($schema && !empty($schemaName)) {
 				if (false == strstr($table, '.')) {
 					return $this->name($schemaName) . '.' . $this->name($table);
 				}
 			}
 			return $this->name($table);
 		}
-		if ($schema && isset($schemaName)) {
+		if ($schema && !empty($schemaName)) {
 			if (false == strstr($table, '.')) {
 				return $schemaName . '.' . $table;
 			}