Account for key encoding

Author: gukoff

Lib/os.py

@@ -745,8 +745,9 @@ def __repr__(self):
     def clear(self):
         while self._data:
             for key in list(self._data):
+                unsetenv(key)
                 try:
-                    del self[key]
+                    del self._data[key]
                 except KeyError:
                     pass