iter_lines is still broken?

I don't understand.

I can't iterate "\r\n" because "\r" and "\n" can be read into different chunks.

But I can't even get solve this problem by explicitly setting the final delimiter "\n"

  for line in (_.strip() for _ in resp.iter_lines(delimiter=b"\n")):
      print(line)

because if chunk end with "\r\n", then lines = chunk.split(delimiter) in iter_lines append empty extra line (but chunk.splitlines() not)

the same problem and just with "\n" - if chunk end with delimiter, then we get an extra empty line. Which forces you to set a large buffer size if line length is unknown

So if the split(...) adds an extra line, why not remove it?

    if delimiter:
        lines = chunk.split(delimiter)
        if lines and not lines[-1]:
            lines.pop(-1)
    else:
        lines = chunk.splitlines()

Start at the iter_lines entry point and trace how chunks are split when a delimiter ends a chunk or when \r\n spans chunks. Reproduce both cases and add or update coverage for the observed behavior; done means iteration does not emit an unintended empty line while preserving delimiters that belong to the next chunk.