Fix check on folder existance in container

We cannot test on host machine for a path that only exists in
the container and expect to have proper behavior.

drush.py

@@ -76,9 +76,8 @@ def aliases():
     drush_aliases = env.site_drush_aliases
     workspace = env.workspace
 
-    if not os.path.exists(drush_aliases):
-        dk_run(env.services['php'], user='root',
-               cmd='mkdir {}'.format(drush_aliases))
+    dk_run(env.services['php'], user='root',
+           cmd='if [ ! -e {} ]; then mkdir {}; fi;'.format(drush_aliases, drush_aliases))
 
     if os.path.exists('{}/aliases.drushrc.php'.format(drush_aliases)):
         dk_run(env.services['php'], user='root',