This is a review from Review Bot.
  Tool: PEP8 Style Checker
  Processed Files:
    reviewboard/changedescs/models.py
    reviewboard/reviews/models.py
  Ignored Files:

Col: 80
 E501 line too long (98 > 79 characters)

Col: 1
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Col: 80
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Col: 30
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Col: 72
 E231 missing whitespace after ','

Col: 9
 E301 expected 1 blank line, found 0

Col: 80
 E501 line too long (82 > 79 characters)

Col: 35
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Col: 80
 E501 line too long (90 > 79 characters)

This is a review from Review Bot.
  Tool: PEP8 Style Checker
  Processed Files:
    reviewboard/changedescs/models.py
    reviewboard/reviews/models.py
  Ignored Files:

Col: 67
 W291 trailing whitespace

Col: 30
 E127 continuation line over-indented for visual indent

Col: 30
 E128 continuation line under-indented for visual indent

Col: 50
 W291 trailing whitespace

Col: 21
 E128 continuation line under-indented for visual indent

Col: 68
 W291 trailing whitespace

This is a review from Review Bot.
  Tool: PEP8 Style Checker
  Processed Files:
    reviewboard/changedescs/models.py
    reviewboard/reviews/models.py
  Ignored Files:

Col: 29
 E128 continuation line under-indented for visual indent

Col: 25
 E128 continuation line under-indented for visual indent

This is a review from Review Bot.
  Tool: PEP8 Style Checker
  Processed Files:
    reviewboard/changedescs/models.py
    reviewboard/reviews/models.py
  Ignored Files:

Col: 30
 E128 continuation line under-indented for visual indent

According to PEP-8, imports should be broken up into three groups, each separated by a blank line (standard library, third-party libraries, this package).

From the "reviewboard" point of view, django/djblets are third-party, and reviewboard is "this package", so we should have a blank line between these.

I think this will break for any model that doesn't have a "username" field (for example, if the target_groups field changes). It's also kind of weird in that the code here is very generic, but you're adding specific knowledge of types that are elsewhere in the codebase (the idea is that "reviews" depends on "changedescs", not the other way around).

I believe a better solution would be to pass in a callable instead of a boolean:

def record_field_change(self, field, old_value, new_value,
                        name_field=None, get_item_url_func=None):

....


if name_field:
    results = []
    for item in list(items):
        if get_item_url_func:
            url = get_item_url_func(item)
        else:
            url = item.get_absolute_url()
        results.append((getattr(item, name_field),
                        get_item_url_func(item),
                        item.id))
    return results

....

That way we can encode knowledge of the "user" type in reviews/models.py where we know we're building a set of the changed users.