renewal-script: Make it not mail if there are no members needing renewal

bin/mail_renewals_to_foundation_list.py

@@ -60,6 +60,10 @@ def main(options=None):
 
 
     members = get_members_which_need_renewal('month')
+    if not members:
+        log.warn('No one needs renewals! :-)')
+    
+    else: # We do have members
         emailtext = format_members_for_mail(members)
         
         today = datetime.date.today()