Remove unused sys & fallback pathlib (3.5+) imports.

IPython/lib/tests/test_display.py

@@ -14,11 +14,7 b''
 #-----------------------------------------------------------------------------
 from tempfile import NamedTemporaryFile, mkdtemp
 from os.path import split, join as pjoin, dirname
-import sys
-try:
-    import pathlib
-except ImportError:
-    pass
+import pathlib
 from unittest import TestCase, mock
 import struct
 import wave