fix glitch with assemble_threshold, avoid division by zero
fix glitch with assemble_threshold, avoid division by zero

andreamola/dealii,YongYang86/dealii,maieneuro/dealii,angelrca/dealii,YongYang86/dealii,ESeNonFossiIo/dealii,shakirbsm/dealii,Arezou-gh/dealii,pesser/dealii,johntfoster/dealii,JaeryunYim/dealii,maieneuro/dealii,sriharisundar/dealii,msteigemann/dealii,shakirbsm/dealii,lpolster/dealii,maieneuro/dealii,adamkosik/dealii,sriharisundar/dealii,EGP-CIG-REU/dealii,mac-a/dealii,nicolacavallini/dealii,natashasharma/dealii,adamkosik/dealii,spco/dealii,rrgrove6/dealii,JaeryunYim/dealii,mac-a/dealii,maieneuro/dealii,danshapero/dealii,andreamola/dealii,naliboff/dealii,nicolacavallini/dealii,spco/dealii,kalj/dealii,rrgrove6/dealii,shakirbsm/dealii,msteigemann/dealii,sairajat/dealii,lpolster/dealii,natashasharma/dealii,shakirbsm/dealii,jperryhouts/dealii,jperryhouts/dealii,jperryhouts/dealii,rrgrove6/dealii,Arezou-gh/dealii,shakirbsm/dealii,ibkim11/dealii,ESeNonFossiIo/dealii,EGP-CIG-REU/dealii,danshapero/dealii,sairajat/dealii,nicolacavallini/dealii,ibkim11/dealii,adamkosik/dealii,Arezou-gh/dealii,sairajat/dealii,nicolacavallini/dealii,lue/dealii,adamkosik/dealii,naliboff/dealii,rrgrove6/dealii,gpitton/dealii,danshapero/dealii,naliboff/dealii,sriharisundar/dealii,sriharisundar/dealii,lue/dealii,pesser/dealii,andreamola/dealii,lpolster/dealii,lpolster/dealii,ESeNonFossiIo/dealii,johntfoster/dealii,rrgrove6/dealii,johntfoster/dealii,YongYang86/dealii,kalj/dealii,johntfoster/dealii,naliboff/dealii,naliboff/dealii,Arezou-gh/dealii,EGP-CIG-REU/dealii,adamkosik/dealii,kalj/dealii,lue/dealii,msteigemann/dealii,msteigemann/dealii,gpitton/dealii,gpitton/dealii,pesser/dealii,andreamola/dealii,spco/dealii,angelrca/dealii,lpolster/dealii,lpolster/dealii,danshapero/dealii,lpolster/dealii,ESeNonFossiIo/dealii,sairajat/dealii,mac-a/dealii,YongYang86/dealii,gpitton/dealii,JaeryunYim/dealii,JaeryunYim/dealii,mac-a/dealii,pesser/dealii,andreamola/dealii,danshapero/dealii,danshapero/dealii,ESeNonFossiIo/dealii,gpitton/dealii,EGP-CIG-REU/dealii,rrgrove6/dealii,JaeryunYim/dealii,ibkim11/dealii,jperryhouts/dealii,EGP-CIG-REU/dealii,maieneuro/dealii,YongYang86/dealii,ESeNonFossiIo/dealii,lue/dealii,msteigemann/dealii,natashasharma/dealii,ibkim11/dealii,lue/dealii,jperryhouts/dealii,natashasharma/dealii,spco/dealii,jperryhouts/dealii,natashasharma/dealii,angelrca/dealii,mac-a/dealii,gpitton/dealii,sairajat/dealii,JaeryunYim/dealii,jperryhouts/dealii,lue/dealii,johntfoster/dealii,Arezou-gh/dealii,shakirbsm/dealii,natashasharma/dealii,andreamola/dealii,sairajat/dealii,sriharisundar/dealii,kalj/dealii,gpitton/dealii,kalj/dealii,msteigemann/dealii,rrgrove6/dealii,angelrca/dealii,YongYang86/dealii,pesser/dealii,spco/dealii,Arezou-gh/dealii,sairajat/dealii,maieneuro/dealii,mac-a/dealii,sriharisundar/dealii,spco/dealii,JaeryunYim/dealii,pesser/dealii,shakirbsm/dealii,EGP-CIG-REU/dealii,nicolacavallini/dealii,mac-a/dealii,spco/dealii,johntfoster/dealii,EGP-CIG-REU/dealii,andreamola/dealii,msteigemann/dealii,ESeNonFossiIo/dealii,ibkim11/dealii,natashasharma/dealii,sriharisundar/dealii,maieneuro/dealii,ibkim11/dealii,adamkosik/dealii,johntfoster/dealii,kalj/dealii,angelrca/dealii,Arezou-gh/dealii,danshapero/dealii,nicolacavallini/dealii,nicolacavallini/dealii,naliboff/dealii,naliboff/dealii,angelrca/dealii,kalj/dealii,YongYang86/dealii,angelrca/dealii,pesser/dealii,ibkim11/dealii,adamkosik/dealii,lue/dealii