All contributions to Buildbot must be licensed under the GPLv2. However, there is no copyright assignment. Please add the following header to each new file:

# This file is part of Buildbot.  Buildbot is free software: you can
# redistribute it and/or modify it under the terms of the GNU General Public
# License as published by the Free Software Foundation, version 2.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc., 51
# Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
# Copyright Buildbot Team Members

You may also add a copyright for yourself or your company (as appropriate), e.g.,:

# Portions Copyright Buildbot Team Members
# Portions Copyright 2008 J. Random Hacker

Do not include a date in the "Buildbot Team Members" copyright line.