Revert r85801. The test ought to pass without rounding.
diff --git a/Lib/test/test_tarfile.py b/Lib/test/test_tarfile.py
index fd7ac2b..3a217dc 100644
--- a/Lib/test/test_tarfile.py
+++ b/Lib/test/test_tarfile.py
@@ -345,7 +345,7 @@
                 if sys.platform != "win32":
                     # Win32 has no support for fine grained permissions.
                     self.assertEqual(tarinfo.mode & 0o777, os.stat(path).st_mode & 0o777)
-                self.assertEqual(tarinfo.mtime, int(os.path.getmtime(path)))
+                self.assertEqual(tarinfo.mtime, os.path.getmtime(path))
         finally:
             tar.close()