Test the way an entry with a related enantiomer entry is handled when the
related enantiomer entry is not explicitly marked using the relevant COD
data items (i.e. _cod_related_enantiomer_entry.code,
_cod_related_enantiomer_entry_code, _cod_enantiomer_of).
Both the original entry and its enantiomer should be recognised as matching
COD entries.
