`ptipython` ignoring classic prompt setting

[citizen428]

It seems I can't get ptipython to use the classic mode, no matter what I try.

• My config.py sets repl.prompt_style = "classic"
• My ipython_config.py enables doctest mode via c.InteractiveShellApp.exec_lines.

It seems everything is configured correctly but it still always starts with ipython style prompts:

❯ ptipython
Exception reporting mode: Plain
Doctest mode is: ON
In [1]: import IPython
In [2]: ip = IPython.get_ipython()
In [3]: ip.prompts
<IPython.terminal.prompts.ClassicPrompts object at 0x108497ad0>

Starting ipython directly shows the classic prompt.

[citizen428]

@jonathanslenders I'm not sure the README PR resolved this issue, maybe the Resolves #xxxx line at the top was wrong?