Allow Bucket.load() to work on cross-account buckets (boto#1064)

* Make s3.Bucket.load() more accepting of failure

This will cause it to no longer fail if creation_date
can't be found via ListBuckets (boto#1063)

* Only swallow ListBuckets AccessDenied errors

boto3/s3/inject.py

@@ -64,15 +64,19 @@ def bucket_load(self, *args, **kwargs):
 
     # We can't actually get the bucket's attributes from a HeadBucket,
     # so we need to use a ListBuckets and search for our bucket.
-    response = self.meta.client.list_buckets()
-    for bucket_data in response['Buckets']:
-        if bucket_data['Name'] == self.name:
-            self.meta.data = bucket_data
-            break
-    else:
-        raise ClientError({'Error': {'Code': '404', 'Message': 'NotFound'}},
-                          'ListBuckets')
-
+    # However, we may fail if we lack permissions to ListBuckets
+    # or the bucket is in another account. In which case, creation_date
+    # will be None.
+    self.meta.data = {}
+    try:
+        response = self.meta.client.list_buckets()
+        for bucket_data in response['Buckets']:
+            if bucket_data['Name'] == self.name:
+                self.meta.data = bucket_data
+                break
+    except ClientError as e:
+        if not e.response.get('Error', {}).get('Code') == 'AccessDenied':
+            raise
 
 def object_summary_load(self, *args, **kwargs):
     """

tests/unit/s3/test_inject.py

@@ -70,18 +70,35 @@ def test_bucket_load_finds_bucket(self):
             self.resource.meta.data,
             {'Name': self.resource.name, 'CreationDate': 2})
 
-    def test_bucket_load_raise_error(self):
+    def test_bucket_load_doesnt_find_bucket(self):
         self.resource.name = 'MyBucket'
         self.client.list_buckets.return_value = {
             'Buckets': [
                 {'Name': 'NotMyBucket', 'CreationDate': 1},
                 {'Name': 'NotMine2', 'CreationDate': 2},
             ],
         }
+        inject.bucket_load(self.resource)
+        self.assertEqual(self.resource.meta.data, {})
+
+    def test_bucket_load_encounters_access_exception(self):
+        self.client.list_buckets.side_effect = ClientError(
+            {'Error':
+             {'Code': 'AccessDenied',
+              'Message': 'Access Denied'}},
+            'ListBuckets')
+        inject.bucket_load(self.resource)
+        self.assertEqual(self.resource.meta.data, {})
+
+    def test_bucket_load_encounters_other_exception(self):
+        self.client.list_buckets.side_effect = ClientError(
+            {'Error':
+             {'Code': 'ExpiredToken',
+              'Message': 'The provided token has expired.'}},
+            'ListBuckets')
         with self.assertRaises(ClientError):
             inject.bucket_load(self.resource)
 
-
 class TestBucketTransferMethods(unittest.TestCase):
 
     def setUp(self):