Fix some errors that #7566 introduced on non-Windows platforms due to

an ImportError. Rearranged the import, faked out the implementation when
the import fails, and reorganized a test that depends on Win32 behavior.

Lib/ntpath.py

@@ -10,7 +10,6 @@ import sys
 import stat
 import genericpath
 from genericpath import *
-from nt import _getfileinformation
 
 __all__ = ["normcase","isabs","join","splitdrive","split","splitext",
            "basename","dirname","commonprefix","getsize","getmtime",
@@ -656,4 +655,10 @@ def samefile(f1, f2):
 
 def sameopenfile(f1, f2):
     """Test whether two file objects reference the same file"""
+    try:
+        from nt import _getfileinformation
         return _getfileinformation(f1) == _getfileinformation(f2)
+    except ImportError:
+        # On other operating systems, return True if the file descriptors
+        # are the same.
+        return f1 == f2

Lib/test/test_ntpath.py

@@ -1,5 +1,6 @@
 import ntpath
 import os
+import sys
 from test.support import TestFailed
 from test import support, test_genericpath
 from tempfile import TemporaryFile
@@ -244,7 +245,8 @@ class TestNtpath(unittest.TestCase):
             self.assertTrue(ntpath.sameopenfile(tf1.fileno(), tf1.fileno()))
             # Make sure different files are really different
             self.assertFalse(ntpath.sameopenfile(tf1.fileno(), tf2.fileno()))
-            # Make sure invalid values don't cause issues
+            # Make sure invalid values don't cause issues on win32
+            if sys.platform == "win32":
                 with self.assertRaises(ValueError):
                     # Invalid file descriptors shouldn't display assert
                     # dialogs (#4804)