replace unnecessary use of `io.IncrementalNewlineDecoder` in code.
Some uses of the `decode` method were also incorrect without the `final=True` argument.

In any case, the use of an incremental newline decoder is not required

Can you describe what the problem is?
Is it incorrect in some cases?  Is it inefficient?

Without a statement of the issue, we can’t discuss a solution :)

Some uses of the `decode` method of `io.IncrementalNewlineDecoder` were incorrect without the `final=True` argument.
One way to fix it would be to add the `final=True` in all cases.
But the incremental decoding feature is not used, so I decided to replace it with stateless non-incremental newline decoders.

If the old code is incorrect, can you give an example where it fails? Is it possible to write a unit test demonstrating that the current behavior is wrong?

The old code has an incorrect usage of `io.IncrementalNewlineDecoder`. Since the `decode` method is called only once, is it the final call and needs the `final=True` argument as documented in https://docs.python.org/dev/library/codecs.html#codecs.IncrementalDecoder.decode

It happens that in those cases, the results are correct in spite of the incorrect usage.