Ensure flags are included in the mass BZ query
    
    While updating my test instance today I noticed a bunch of
    warnings from python-bugzilla like this:
    
    Bug 1371338 missing attribute 'flags' - doing implicit refresh().
    This will be slow, if you want to avoid this, properly use
    query/getbug include_fields, and set bugzilla.bug_autorefresh =
    False to force failure.
    
    This happens in `update_milestone()` in bug_sync. We do a mass
    query for `newbugs` then call `self.extract_information()` on
    each individual bug. That in turn looks at the bug's flags to
    determine whether `needinfo` is set. But it appears that, by
    default, the flags are not included in the result of the mass
    `newbugs` query, so python-bugzilla is doing an extra individual
    query for each bug to get the flags. This is obviously slow and
    produces needless load on the server.
    
    To avoid this, it seems that we can just specify `extra_fields`
    in the code that ultimately produces the query we use to get
    `newbugs`. That way each `newbug` already has its flags and no
    re-query is necessary.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>