Remote field not updated when object changes

[cristina0botez]

Scenario:

class Poll:
   pass

class Answer:
    poll = models.ForeignKey(Poll, related_name='answers')

When creating an answer for a poll, an additional historical record should be created for the Poll object recording 'answers': '<ID_OF_ANSWER>, <ID_OF_ANSWER>,..., <ID_OF_NEW_ANSWER>'.
This change will be made only after the poll object is saved.