Extract the members of a group from /etc/group.

def ParseGroupEntry(self, line):
    """Extract the members of a group from /etc/group."""
    fields = ("name", "passwd", "gid", "members")
    if line:
      rslt = dict(zip(fields, line.split(":")))
      name = rslt["name"]
      group = self.entry.setdefault(name, rdf_client.Group(name=name))
      group.pw_entry.store = self.GetPwStore(rslt["passwd"])
      if group.pw_entry.store == self.base_store:
        group.pw_entry.hash_type = self.GetHashType(rslt["passwd"])
      # If the group contains NIS entries, they may not have a gid.
      if rslt["gid"]:
        group.gid = int(rslt["gid"])
      group.members = set(rslt["members"].split(","))