Patch #1181: add os.environ.clear() method.

Doc/library/os.rst

@@ -117,7 +117,11 @@ process and user.
 
    If the platform supports the :func:`unsetenv` function, you can delete items in
    this mapping to unset environment variables. :func:`unsetenv` will be called
-   automatically when an item is deleted from ``os.environ``.
+   automatically when an item is deleted from ``os.environ``, and when
+   :meth:`os.environ.clear` is called.
+
+   .. versionchanged:: 2.6
+      Also unset environment variables when calling :meth:`os.environ.clear`.
 
 
 .. function:: chdir(path)

Lib/os.py

@@ -446,6 +446,10 @@ else:
                 def __delitem__(self, key):
                     unsetenv(key)
                     del self.data[key.upper()]
+                def clear(self):
+                    for key in self.data.keys():
+                        unsetenv(key)
+                        del self.data[key]
             def has_key(self, key):
                 return key.upper() in self.data
             def __contains__(self, key):
@@ -503,6 +507,10 @@ else:
                 def __delitem__(self, key):
                     unsetenv(key)
                     del self.data[key]
+                def clear(self):
+                    for key in self.data.keys():
+                        unsetenv(key)
+                        del self.data[key]
             def copy(self):
                 return dict(self)