Comment 4 for bug 927539

I end up with no entry on my diagonal all the time when using assembly over subdomains. I've been using ident_zeros to get around this but find that on the first call it is painfully slow, which I suspect (though I haven't looked into it) is due to expanding the size of the sparsity after its initial allocation. If it were possible to have an option to leave the diagonal entries in the sparsity on the first assembly this would be great!