Merge pull request #538 from Deltachaos/fix_537

Fixes update of shared files with mirall because it dose not update all ...

lib/filecache.php

@@ -137,6 +137,7 @@ class OC_FileCache{
 		}
 		$arguments[]=$id;
 
+		if(!empty($queryParts)) {
 			$sql = 'UPDATE `*PREFIX*fscache` SET '.implode(' , ', $queryParts).' WHERE `id`=?';
 			$query=OC_DB::prepare($sql);
 			$result=$query->execute($arguments);
@@ -144,6 +145,7 @@ class OC_FileCache{
 				OC_Log::write('files', 'error while updating file('.$id.') in cache', OC_Log::ERROR);
 			}
 		}
+	}
 
 	/**
 	 * register a file move in the cache