Update tox configuration so warning message is not printed.
diff --git a/tox.ini b/tox.ini
index 8d89dcd..c1334b0 100644
--- a/tox.ini
+++ b/tox.ini
@@ -21,6 +21,7 @@
     py3.5: python3.5
     py3.6: python3.6
 whitelist_externals = cp
+                      scripts/*.sh
 
 [testenv:pypypy3]
 commands = cp libcloud/test/secrets.py-dist libcloud/test/secrets.py