Fix enforcing extension for custom `-refDB`
Fix enforcing extension for custom `-refDB`

anilthanki/tgac-galaxytools,TGAC/earlham-galaxytools,TGAC/earlham-galaxytools,TGAC/earlham-galaxytools,anilthanki/tgac-galaxytools,anilthanki/tgac-galaxytools,TGAC/earlham-galaxytools,anilthanki/tgac-galaxytools,anilthanki/tgac-galaxytools,TGAC/earlham-galaxytools