Catch AttributeError in utils.super_len (#5239)

* Catch AttributeError in utils.super_len

This allows it to handle files obtained via `Tarfile.extractfile()`.

tests/test_utils.py

@@ -4,6 +4,7 @@ import os
 import copy
 import filecmp
 from io import BytesIO
+import tarfile
 import zipfile
 from collections import deque
 
@@ -86,6 +87,18 @@ class TestSuperLen:
             assert super_len(fd) == 4
         assert len(recwarn) == warnings_num
 
+    def test_tarfile_member(self, tmpdir):
+        file_obj = tmpdir.join('test.txt')
+        file_obj.write('Test')
+
+        tar_obj = str(tmpdir.join('test.tar'))
+        with tarfile.open(tar_obj, 'w') as tar:
+            tar.add(str(file_obj), arcname='test.txt')
+
+        with tarfile.open(tar_obj) as tar:
+            member = tar.extractfile('test.txt')
+            assert super_len(member) == 4
+
     def test_super_len_with__len__(self):
         foo = [1,2,3,4]
         len_foo = super_len(foo)