def reported_br_params(path1, path2):
  """Return (SUBBRANCH_RPATH, SUBBRANCH_FULLPATH).

     Parameters are either (OUTER_BRANCH_FULLPATH, SUBBRANCH_RPATH) or for
     a first-level branch (SUBBRANCH_RPATH, None). 'FULLPATH' means relpath
     from the repo root; 'RPATH' means relpath from the outer branch.
  """
  if path2 is None:
    subbranch_rpath = path1
    subbranch_fullpath = path1
  else:
    subbranch_rpath = path2
    subbranch_fullpath = path1 + '/' + path2
  return subbranch_rpath, subbranch_fullpath