Release locks after class in tests

tests/lib/testcase.php

 		self::tearDownAfterClassCleanFileCache();
 		self::tearDownAfterClassCleanStrayDataFiles($dataDir);
 		self::tearDownAfterClassCleanStrayHooks();
+		self::tearDownAfterClassCleanStrayLocks();
 
 		parent::tearDownAfterClass();
 	}
 		\OC_Hook::clear();
 	}
 
+	/**
+	 * Clean up the list of locks
+	 */
+	static protected function tearDownAfterClassCleanStrayLocks() {
+		\OC::$server->getLockingProvider()->releaseAll();
+	}
+
 	/**
 	 * Login and setup FS as a given user,
 	 * sets the given user as the current user.