Fix bug in ERS97 implementation

Do not attempt to elect candidates already elected

pyRCV2/method/base_stv.py

@@ -597,6 +597,7 @@ class BaseSTVCounter:
 				if self.options['quota_mode'] == 'ers97':
 					self.compute_quota()
 					self.elect_meeting_quota() # Repeat as the vote required for election may have changed
+					return
 	
 	# -----------------
 	# UTILITY FUNCTIONS