Keep a list of candidate species-sets and try them all
Keep a list of candidate species-sets and try them all

This is needed when the Runnable is configured with a species-set name,
because several sets may share the same name, and we cannot tell which one
is to be used until we check the existence of MLSSs

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