fixed bug which would cause sites with pages without parents to mess up Nanoc::Site#load_data
fixed bug which would cause sites with pages without parents to mess up Nanoc::Site#load_data

--HG--
extra : convert_revision : svn%3A177060d3-6165-4ab0-95eb-642399a075a8/nanoc/trunk%40687

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