fix: prevent input side-effects in processor text args

[nph4rd]

What does this PR do?

Fixes input side-effects in multiple processor classes when the text input is a list.

Fixes #36865

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Who can review?

@ArthurZucker @qubvel

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[zucchini-nlp]

For me it seems the problem is in how qwen2-vl is written. Other VLMs do not override the text and use save expanded prompts in a new list. So rewriting Qwen2-VL is more preferable than adding a copy() in all processors

[nph4rd]

@zucchini-nlp - thanks for the comment! 😃

Just to be clear: I added the copy() in all the processors that have a similar pattern like:

for sample in text:
    sample = sample.replace(...)

This isn't just Qwen-based processors. One example: Pixtral.

So, if I understand correctly, you're saying it'd be preferrable to change all these processors to have something like:

expanded_samples = []
for sample in text:
    expanded_sample =  sample.replace(...)
    expanded_samples.append(expanded_sample)

Correct?

I must say: I don't find that cleaner 🤔 and if it's for the sake of consistency then I'd suggest adding the .copy() to the rest of the VLM processors. That would imply less changed lines and better readability IMO -- e.g. no variable name change. However, if what you're saying is the consensus then I'd be happy to make the changes.

[nph4rd]

That would imply less changed lines

ha! 🤔 don't think that's true. My bad.

Still, it seems a bit less readable to me.

Again, happy to go either way if that's your suggestion.

[zucchini-nlp]

@nph4rd not a big difference for me, I am good whichever way as long as it doesn't do in-place modifications. I was surprised to see so many processor's changed, while the error is applicable only to Qwen VL

Let's also see what @molbap thinks