bugfix: when several GenomeDBs share the same taxon_id and multifurcation_deletes_all_subnodes is used, we need to make sure the sub-tree remains flat
bugfix: when several GenomeDBs share the same taxon_id and multifurcation_deletes_all_subnodes is used, we need to make sure the sub-tree remains flat

Ensembl/ensembl-compara,Ensembl/ensembl-compara,Ensembl/ensembl-compara,Ensembl/ensembl-compara,Ensembl/ensembl-compara,Ensembl/ensembl-compara,Ensembl/ensembl-compara,Ensembl/ensembl-compara