Made the error raised from a failed Redleaf::Graph#append marginally more informative.
Made the error raised from a failed Redleaf::Graph#append marginally more informative.

--HG--
extra : convert_revision : svn%3Adfad69a5-955d-dd11-a525-000e0c4bc663/trunk%4063

ged/redleaf,ged/redleaf,ged/redleaf