rpcauth script fails

[jonasnick]

$ cd examples
$ rm -rf ./secrets
$ nix-shell
Traceback (most recent call last):
  File "/nix/store/g7d8s8kywpigdbzp8r5n2gzqy5m903wb-rpcauth.py", line 6, in <module>
    from argparse import ArgumentParser
  File "/nix/store/r94aa2gj4drkhfvkm2p4ab6cblb6kxlq-python3-3.7.6/lib/python3.7/argparse.py", line 87, in <module>
    import re as _re
  File "/nix/store/r94aa2gj4drkhfvkm2p4ab6cblb6kxlq-python3-3.7.6/lib/python3.7/re.py", line 143, in <module>
    class RegexFlag(enum.IntFlag):
AttributeError: module 'enum' has no attribute 'IntFlag'

As a result, the HMAC files in the secrets directory are empty.