Whitelist mkdir. Fixes #1713

Author: jaraco

tox.ini

@@ -22,6 +22,7 @@ setenv =
 extras =
     testing
     routes_dispatcher
+whitelist_externals = mkdir
 
 [testenv:cheroot-master]
 deps = git+git://github.com/cherrypy/cheroot.git@master#egg=cheroot