Update os/os.test.py

Co-authored-by: Sebastien Binet <[email protected]>

Author: glaukiol1

os/os.test.py

@@ -47,7 +47,7 @@ def _fail(test_name):
     passed_tests = passed_tests + 1
 else:
     _fail("os.error == OSError")
-    failed = failed + 1
+    failed += 1
 
 if os.environ.get("HOME") != None:
     _pass('os.environ.get("HOME") != None')