fix tox problem with sith tests

tox.ini

@@ -20,4 +20,5 @@ commands =
     coverage report
 [testenv:sith]
 commands =
+    {envpython} -c "import os; a='{envtmpdir}'; os.path.exists(a) or os.makedirs(a)"
     {envpython} sith.py --record {envtmpdir}/record.json random {posargs:jedi}