overset: normalisation of new matrix entries for interpolated/hole cells does not include remote contributions

Summary

Division by zero (producing sigfpe) in the linear solver for p in some decompositions.

Steps to reproduce

basic/overPotentialFoam/cylinder/cylinderAndBackground and use e.g.

//- The total number of domains (mandatory)
numberOfSubdomains  30;

//- The decomposition method (mandatory)
method          random;

The idea is that it creates cells where all the neighbours are on other processors. This leads to a zero normalisation in the matrix rewrite.

Environment information

• OpenFOAM version : v1906, develop

Possible fixes

When inserting the new matrix 'rows' for interpolated and/or hole cells make sure to use a normalisation that includes the remote contributions.