bug in 'health' check

[bendemott]

  RUNNING: check_overseer_election
 ** (<type 'exceptions.TypeError'>) not enough arguments for format string -   File "C:\Python27\lib\site-packages\solrzkutil\__init__.py", line 737, in health_check
    errors = check(zk_client)
;
  File "C:\Python27\lib\site-packages\solrzkutil\healthy.py", line 1191, in check_overseer_election
    errors.append("overseer leader [%s] contents vary: [%s]" % OVERSEER_ELECT_ELECTION_PATH, ', '.join(overseer_data_unique))