Only call $this->filesize() for files.

lib/private/files/storage/local.php

@@ -89,7 +89,7 @@ if (\OC_Util::runningOnWindows()) {
 		public function stat($path) {
 			$fullPath = $this->datadir . $path;
 			$statResult = stat($fullPath);
-			if (PHP_INT_SIZE === 4) {
+			if (PHP_INT_SIZE === 4 && !$this->is_dir($path)) {
 				$filesize = $this->filesize($path);
 				$statResult['size'] = $filesize;
 				$statResult[7] = $filesize;

lib/private/files/storage/mappedlocal.php

@@ -111,7 +111,7 @@ class MappedLocal extends \OC\Files\Storage\Common {
 	public function stat($path) {
 		$fullPath = $this->buildPath($path);
 		$statResult = stat($fullPath);
-		if (PHP_INT_SIZE === 4) {
+		if (PHP_INT_SIZE === 4 && !$this->is_dir($path)) {
 			$filesize = $this->filesize($path);
 			$statResult['size'] = $filesize;
 			$statResult[7] = $filesize;