message: Fix zipfile path for MacOS builds.
  For some reason, the zipfile module on Macs appears to work differently and
  complains about the whl file we are trying to extract not being found.
diff: @@ -60,7 +60,7 @@ def copy_binary(directory, origin_tag, new_tag, version, gpu=False):
  package = "tf_nightly"
  origin_binary = BINARY_STRING_TEMPLATE % (package, version, origin_tag)
  new_binary = BINARY_STRING_TEMPLATE % (package, version, new_tag)
  - zip_ref = zipfile.ZipFile(directory + origin_binary, "r")
  + zip_ref = zipfile.ZipFile(os.path.join(directory, origin_binary), "r")
  try:
  tmpdir = tempfile.mkdtemp()
  @@ -115,6 +115,7 @@ def main():
  args = parser.parse_args()
  # Argument checking
  + args.filename = os.path.abspath(args.filename)
  check_existence(args.filename)
  regex_groups = re.search(TF_NIGHTLY_REGEX, args.filename)
  directory = regex_groups.group(1)
  