bootstrap : cerbero bootstrap failed with build_tools

If setuptools.version contains a string, an error occurs.

Python 3.8.5 (default, Sep  4 2020, 02:22:02)
>>> import setuptools.version as stv
>>> stv.__version__
'50.3.2.post20201201'

Error Log

(base) ☁  cerbero [master] ./cerbero-uninstalled bootstrap
Build tools install prefix will be /Users/soo/soo-works/media-server/cerbero/build/build-tools
Install prefix will be /Users/soo/soo-works/media-server/cerbero/build/dist/darwin_x86_64
File /Users/soo/.cache/cerbero-sources/cpanm already downloaded.
Installing XML::Parser, may require a password for running 'sudo /Users/soo/.cache/cerbero-sources/cpanm XML::Parser'
Password:
XML::Parser is up to date. (2.46)
Traceback (most recent call last):
  File "<string>", line 20, in <module>
  File "/Users/soo/soo-works/media-server/cerbero/cerbero/main.py", line 183, in main
    Main(sys.argv[1:])
  File "/Users/soo/soo-works/media-server/cerbero/cerbero/main.py", line 53, in __init__
    self.run_command()
  File "/Users/soo/soo-works/media-server/cerbero/cerbero/main.py", line 152, in run_command
    res = commands.run(command, self.config, self.args)
  File "/Users/soo/soo-works/media-server/cerbero/cerbero/commands/__init__.py", line 78, in run
    return _commands[command].run(config, args)
  File "/Users/soo/soo-works/media-server/cerbero/cerbero/commands/bootstrap.py", line 79, in run
    bootstrapper.start(jobs=args.jobs)
  File "/Users/soo/soo-works/media-server/cerbero/cerbero/bootstrap/build_tools.py", line 125, in start
    self.insert_python_site()
  File "/Users/soo/soo-works/media-server/cerbero/cerbero/bootstrap/build_tools.py", line 103, in insert_python_site
    version = [int(v) for v in stv.__version__.split('.')]
  File "/Users/soo/soo-works/media-server/cerbero/cerbero/bootstrap/build_tools.py", line 103, in <listcomp>
    version = [int(v) for v in stv.__version__.split('.')]
ValueError: invalid literal for int() with base 10: 'post20201201'