not expecting errors in these tests. let them pass errors.

tests/test_uninstall.py

@@ -14,9 +14,9 @@ def test_simple_uninstall():
 
     """
     env = reset_env()
-    result = run_pip('install', 'INITools==0.2', expect_error=True)
+    result = run_pip('install', 'INITools==0.2')
     assert join(env.site_packages, 'initools') in result.files_created, sorted(result.files_created.keys())
-    result2 = run_pip('uninstall', 'INITools', '-y', expect_error=True)
+    result2 = run_pip('uninstall', 'INITools', '-y')
     assert_all_changes(result, result2, [env.venv/'build', 'cache'])