tidy the condition

Author: Vladimir Kotal

opengrok-tools/src/test/python/test_command_sequence.py

@@ -134,7 +134,7 @@ def test_cleanup_exception():
 # /bin/cat returns 2 on Solaris
 @pytest.mark.skipif(not os.path.exists('/usr/bin/touch') or
                     not os.path.exists('/bin/cat') or
-                    not sys.platform != "sunos5",
+                    sys.platform == "sunos5",
                     reason="requires Unix")
 def test_cleanup():
     with tempfile.TemporaryDirectory() as tmpdir: