fix: closes gh-163.
fix: closes gh-163.

The bug resulted from an interaction between node naming and
topological sort (which does not guarantee node order for nodes at
the same level of a DAG) on approximately 20-30% of runs in
workflows that contained multiple iterables.

blakedewey/nipype,pearsonlab/nipype,carolFrohlich/nipype,iglpdc/nipype,arokem/nipype,grlee77/nipype,iglpdc/nipype,rameshvs/nipype,carolFrohlich/nipype,grlee77/nipype,pearsonlab/nipype,grlee77/nipype,gerddie/nipype,dmordom/nipype,arokem/nipype,FCP-INDI/nipype,wanderine/nipype,mick-d/nipype,carlohamalainen/nipype,mick-d/nipype,arokem/nipype,FredLoney/nipype,mick-d/nipype_source,pearsonlab/nipype,arokem/nipype,FCP-INDI/nipype,FCP-INDI/nipype,fprados/nipype,mick-d/nipype_source,JohnGriffiths/nipype,christianbrodbeck/nipype,rameshvs/nipype,dgellis90/nipype,wanderine/nipype,fprados/nipype,sgiavasis/nipype,glatard/nipype,gerddie/nipype,gerddie/nipype,JohnGriffiths/nipype,Leoniela/nipype,mick-d/nipype,glatard/nipype,glatard/nipype,iglpdc/nipype,dgellis90/nipype,dmordom/nipype,christianbrodbeck/nipype,FredLoney/nipype,FCP-INDI/nipype,fprados/nipype,JohnGriffiths/nipype,sgiavasis/nipype,rameshvs/nipype,carolFrohlich/nipype,mick-d/nipype_source,sgiavasis/nipype,blakedewey/nipype,JohnGriffiths/nipype,Leoniela/nipype,wanderine/nipype,rameshvs/nipype,pearsonlab/nipype,gerddie/nipype,FredLoney/nipype,blakedewey/nipype,wanderine/nipype,carlohamalainen/nipype,carlohamalainen/nipype,grlee77/nipype,Leoniela/nipype,dgellis90/nipype,dmordom/nipype,glatard/nipype,sgiavasis/nipype,blakedewey/nipype,iglpdc/nipype,dgellis90/nipype,carolFrohlich/nipype,mick-d/nipype