Correct the default value of the __import__ level argument to be -1

doc/CHANGES.rst

@@ -16,7 +16,7 @@ Features Added
 ++++++++++++++
 
 - LP #659968: Added support for level argument to the ``__import__`` function
-  as introduced in Python 2.5. Currently only level=0 is supported.
+  as introduced in Python 2.5. Currently only level=-1 is supported.
 
 
 2.12.12 (2010-10-02)

src/AccessControl/ZopeGuards.py

@@ -268,7 +268,7 @@ def guarded_zip(*seqs):
 safe_builtins['zip'] = guarded_zip
 
 def guarded_import(mname, globals=None, locals=None, fromlist=None,
-                   level=0):
+                   level=-1):
     if fromlist is None:
         fromlist = ()
     if '*' in fromlist:
@@ -278,7 +278,7 @@ def guarded_import(mname, globals=None, locals=None, fromlist=None,
     if locals is None:
         locals = {}
     # Refs https://bugs.launchpad.net/zope2/+bug/659968
-    if level != 0:
+    if level != -1:
         raise Unauthorized("Using import with a level specification isn't "
                            "supported by AccessControl: %s" % mname)
 

src/AccessControl/tests/testModuleSecurity.py

@@ -32,13 +32,13 @@ class ModuleSecurityTests(unittest.TestCase):
             if module in sys.modules:
                 del sys.modules[module]
 
-    def assertUnauth(self, module, fromlist, level=0):
+    def assertUnauth(self, module, fromlist, level=-1):
         from zExceptions import Unauthorized
         from AccessControl.ZopeGuards import guarded_import
         self.assertRaises(Unauthorized, guarded_import, module,
                           fromlist=fromlist, level=level)
 
-    def assertAuth(self, module, fromlist, level=0):
+    def assertAuth(self, module, fromlist, level=-1):
         from AccessControl.ZopeGuards import guarded_import
         guarded_import(module, fromlist=fromlist, level=level)
 
@@ -77,7 +77,7 @@ class ModuleSecurityTests(unittest.TestCase):
         self.failUnless('AccessControl.tests.nonesuch' in MS)
 
     def test_level_zero(self):
-        self.assertAuth('AccessControl.tests.public_module', (), level=0)
+        self.assertAuth('AccessControl.tests.public_module', (), level=-1)
 
     def test_level_nonzero(self):
         self.assertUnauth('AccessControl.tests.public_module', (), level=1)