Fix a bug where the lazy node would never evaluate if there were diamond deps

Hello @eford1, @majelbstoat, 

Please review the following commits I made in branch 'nick-lazy5'.

826e297a2f7e2a290701b007ddb095860d0e3bca (2013-09-12 21:19:08 -0400)
Fix a bug where the lazy node would never evaluate if there were diamond deps


R=@eford1
R=@majelbstoat