rrepair: minor improvements of special cases in calc_n_subparts_p1e/*
rrepair: minor improvements of special cases in calc_n_subparts_p1e/*

jvf/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,jvf/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,jvf/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,jvf/scalaris,jvf/scalaris,jvf/scalaris,jvf/scalaris,scalaris-team/scalaris