Also check if the file itself is updatable

apps/files_external/lib/streamwrapper.php

@@ -21,7 +21,7 @@ abstract class StreamWrapper extends Common {
 	}
 
 	public function rmdir($path) {
-		if ($this->file_exists($path) and $this->isDeletable($path)) {
+		if ($this->file_exists($path) && $this->isDeletable($path)) {
 			$dh = $this->opendir($path);
 			while (($file = readdir($dh)) !== false) {
 				if ($this->is_dir($path . '/' . $file)) {

apps/files_external/lib/swift.php

@@ -187,7 +187,7 @@ class Swift extends \OC\Files\Storage\Common {
 	public function rmdir($path) {
 		$path = $this->normalizePath($path);
 
-		if (!$this->is_dir($path) or !$this->isDeletable($path)) {
+		if (!$this->is_dir($path) || !$this->isDeletable($path)) {
 			return false;
 		}
 

lib/private/files/storage/common.php

@@ -95,11 +95,11 @@ abstract class Common implements \OC\Files\Storage\Storage {
 	}
 
 	public function isDeletable($path) {
-		if ($path === '' or $path === '/') {
+		if ($path === '' || $path === '/') {
 			return false;
 		}
 		$parent = dirname($path);
-		return $this->isUpdatable($parent);
+		return $this->isUpdatable($parent) and $this->isUpdatable($path);
 	}
 
 	public function isSharable($path) {