Avoid checking explicitly for iterator and making a copy to nbunch dictionary in subgraph.
Avoid checking explicitly for iterator and making a copy
to nbunch dictionary in subgraph.

--HG--
extra : convert_revision : svn%3A3ed01bd8-26fb-0310-9e4c-ca1a4053419f/networkx/trunk%40238

debsankha/networkx,farhaanbukhsh/networkx,bzero/networkx,nathania/networkx,jtorrents/networkx,yashu-seth/networkx,farhaanbukhsh/networkx,blublud/networkx,JamesClough/networkx,bzero/networkx,sharifulgeo/networkx,RMKD/networkx,jtorrents/networkx,jakevdp/networkx,blublud/networkx,jcurbelo/networkx,ionanrozenfeld/networkx,debsankha/networkx,chrisnatali/networkx,SanketDG/networkx,goulu/networkx,ionanrozenfeld/networkx,jni/networkx,ghdk/networkx,kai5263499/networkx,ghdk/networkx,kernc/networkx,sharifulgeo/networkx,NvanAdrichem/networkx,tmilicic/networkx,jakevdp/networkx,wasade/networkx,aureooms/networkx,dhimmel/networkx,ltiao/networkx,bzero/networkx,andnovar/networkx,Sixshaman/networkx,nathania/networkx,dhimmel/networkx,dmoliveira/networkx,kernc/networkx,chrisnatali/networkx,harlowja/networkx,kai5263499/networkx,jni/networkx,aureooms/networkx,harlowja/networkx,RMKD/networkx,jni/networkx,kernc/networkx,nathania/networkx,dmoliveira/networkx,aureooms/networkx,blublud/networkx,kai5263499/networkx,beni55/networkx,jakevdp/networkx,farhaanbukhsh/networkx,chrisnatali/networkx,debsankha/networkx,sharifulgeo/networkx,harlowja/networkx,OrkoHunter/networkx,dmoliveira/networkx,michaelpacer/networkx,dhimmel/networkx,cmtm/networkx,jfinkels/networkx,ghdk/networkx,ionanrozenfeld/networkx,RMKD/networkx