fixed tiny bug which could cause some extra directories to be created sometimes
fixed tiny bug which could cause some extra directories to be created sometimes

--HG--
extra : convert_revision : svn%3A177060d3-6165-4ab0-95eb-642399a075a8/trunk%4032

nanoc/nanoc,barraq/nanoc,hilohiro/nanoc,RubenVerborgh/nanoc,gjtorikian/nanoc,legallybrown/nanoc,remko/nanoc