old_contents: #!/usr/bin/env python
  # Copyright 2014 The Chromium Authors. All rights reserved.
  # Use of this source code is governed by a BSD-style license that can be
  # found in the LICENSE file.
  
  import argparse
  import sys
  
  import subprocess2
  
  from git_common import run, root, set_config, get_or_create_merge_base, tags
  from git_common import hash_one
  
  
  def main(args):
    parser = argparse.ArgumentParser(
      formatter_class=argparse.ArgumentDefaultsHelpFormatter
    )
    parser.add_argument('branch_name')
    g = parser.add_mutually_exclusive_group()
    g.add_argument('--upstream_current', action='store_true',
                   help='set upstream branch to current branch.')
    g.add_argument('--upstream', metavar='REF', default=root(),
                   help='upstream branch (or tag) to track.')
    g.add_argument('--lkgr', action='store_const', const='lkgr', dest='upstream',
                   help='set basis ref for new branch to lkgr.')
  
    opts = parser.parse_args(args)
  
    try:
      if opts.upstream_current:
        run('checkout', '--track', '-b', opts.branch_name)
      else:
        if opts.upstream in tags():
          # TODO(iannucci): ensure that basis_ref is an ancestor of HEAD?
          run('checkout', '--no-track', '-b', opts.branch_name,
              hash_one(opts.upstream))
          set_config('branch.%s.remote' % opts.branch_name, '.')
          set_config('branch.%s.merge' % opts.branch_name, opts.upstream)
        else:
          # TODO(iannucci): Detect unclean workdir then stash+pop if we need to
          # teleport to a conflicting portion of history?
          run('checkout', '--track', opts.upstream, '-b', opts.branch_name)
      get_or_create_merge_base(opts.branch_name)
    except subprocess2.CalledProcessError as cpe:
      sys.stdout.write(cpe.stdout)
      sys.stderr.write(cpe.stderr)
      return 1
    sys.stderr.write('Switched to branch %s.' % opts.branch_name)
  
  
  if __name__ == '__main__':  # pragma: no cover
    sys.exit(main(sys.argv[1:]))
  
new_contents: #!/usr/bin/env python
  # Copyright 2014 The Chromium Authors. All rights reserved.
  # Use of this source code is governed by a BSD-style license that can be
  # found in the LICENSE file.
  
  import argparse
  import sys
  
  import subprocess2
  
  from git_common import run, root, set_config, get_or_create_merge_base, tags
  from git_common import hash_one
  
  
  def main(args):
    parser = argparse.ArgumentParser(
      formatter_class=argparse.ArgumentDefaultsHelpFormatter
    )
    parser.add_argument('branch_name')
    g = parser.add_mutually_exclusive_group()
    g.add_argument('--upstream_current', action='store_true',
                   help='set upstream branch to current branch.')
    g.add_argument('--upstream', metavar='REF', default=root(),
                   help='upstream branch (or tag) to track.')
    g.add_argument('--lkgr', action='store_const', const='lkgr', dest='upstream',
                   help='set basis ref for new branch to lkgr.')
  
    opts = parser.parse_args(args)
  
    try:
      if opts.upstream_current:
        run('checkout', '--track', '-b', opts.branch_name)
      else:
        if opts.upstream in tags():
          # TODO(iannucci): ensure that basis_ref is an ancestor of HEAD?
          run('checkout', '--no-track', '-b', opts.branch_name,
              hash_one(opts.upstream))
          set_config('branch.%s.remote' % opts.branch_name, '.')
          set_config('branch.%s.merge' % opts.branch_name, opts.upstream)
        else:
          # TODO(iannucci): Detect unclean workdir then stash+pop if we need to
          # teleport to a conflicting portion of history?
          run('checkout', '--track', opts.upstream, '-b', opts.branch_name)
      get_or_create_merge_base(opts.branch_name)
    except subprocess2.CalledProcessError as cpe:
      sys.stdout.write(cpe.stdout)
      sys.stderr.write(cpe.stderr)
      return 1
    sys.stderr.write('Switched to branch %s.\n' % opts.branch_name)
  
  
  if __name__ == '__main__':  # pragma: no cover
    sys.exit(main(sys.argv[1:]))
  
subject: Add newline to git-new-branch output.