Standardize the sys.path fix up and fix a few pylint warnings.

tests/checkout_test.py

Index: tests/checkout_test.py
diff --git a/tests/checkout_test.py b/tests/checkout_test.py
index 1428bd7308729ba54d716815b38f32925953a3e7..5de734a0088ac597770c73ed804ce2cb77375d0e 100755
--- a/tests/checkout_test.py
+++ b/tests/checkout_test.py
@@ -14,8 +14,7 @@ import unittest
 from xml.etree import ElementTree
 
 ROOT_DIR = os.path.dirname(os.path.abspath(__file__))
-BASE_DIR = os.path.join(ROOT_DIR, '..')
-sys.path.insert(0, BASE_DIR)
+sys.path.insert(0, os.path.dirname(ROOT_DIR))
 
 import checkout
 import patch