Add EnvironmentVarGuard to test.test_support. Provides a context manager to
temporarily set or unset environment variables.
diff --git a/Misc/NEWS b/Misc/NEWS
index ba882ef..4f310d8 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -323,6 +323,10 @@
Tests
-----
+- Added test.test_support.EnvironmentVarGuard. It's a class that provides a
+ context manager so that one can temporarily set or unset environment
+ variables.
+
- Added guard_warnings_filter to test.test_support. It returns a context
manager that protects the 'warnings' module's filter from being mutated
once the context has been exited.