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/Lib/test/test_support.py b/Lib/test/test_support.py
index 5973e07..c1b1c69 100644
--- a/Lib/test/test_support.py
+++ b/Lib/test/test_support.py
@@ -532,30 +532,32 @@
a context manager."""
def __init__(self):
- self._environ = os.environ
- self._unset = set()
- self._reset = dict()
+ self._changed = {}
def set(self, envvar, value):
- if envvar not in self._environ:
- self._unset.add(envvar)
- else:
- self._reset[envvar] = self._environ[envvar]
- self._environ[envvar] = value
+ # Remember the initial value on the first access
+ if envvar not in self._changed:
+ self._changed[envvar] = os.environ.get(envvar)
+ os.environ[envvar] = value
def unset(self, envvar):
- if envvar in self._environ:
- self._reset[envvar] = self._environ[envvar]
- del self._environ[envvar]
+ # Remember the initial value on the first access
+ if envvar not in self._changed:
+ self._changed[envvar] = os.environ.get(envvar)
+ if envvar in os.environ:
+ del os.environ[envvar]
def __enter__(self):
return self
def __exit__(self, *ignore_exc):
- for envvar, value in self._reset.iteritems():
- self._environ[envvar] = value
- for unset in self._unset:
- del self._environ[unset]
+ for (k, v) in self._changed.items():
+ if v is None:
+ if k in os.environ:
+ del os.environ[k]
+ else:
+ os.environ[k] = v
+
class TransientResource(object):
diff --git a/Misc/NEWS b/Misc/NEWS
index 472c7e6..28ddebb 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -875,6 +875,10 @@
- Issue #5083: New 'gui' resource for regrtest.
+- 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 2.6 final
==============================