Merged revisions 71875 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

........
  r71875 | walter.doerwald | 2009-04-25 14:15:07 +0200 (Sa, 25 Apr 2009) | 7 lines

  Issue #5837: Certain sequences of calls to set() and unset() for
  support.EnvironmentVarGuard objects restored the environment variables
  incorrectly on __exit__.

  Fix this by recording the initial value of each environment variable on the
  first access in set() or unset().
........
diff --git a/Misc/NEWS b/Misc/NEWS
index e647965..b9fc50a 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -124,6 +124,10 @@
   other modules with both C and Python implementations in the stdlib
   can be adjusted to use it over time.
 
+- Issue #5837: Certain sequences of calls to set() and unset() for
+  support.EnvironmentVarGuard objects restored the environment variables
+  incorrectly on __exit__.
+
 
 What's New in Python 3.1 alpha 2?
 =================================