Copy all join node fields from the override self._inputs to the base self._interface.inputs. Add a better node slot field accessor error message. Clarify a comment.
Copy all join node fields from the override self._inputs to the base self._interface.inputs.
Add a better node slot field accessor error message.
Clarify a comment.

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