bug#29918: 26.0.90; serial-term error in process filter

[Noam Postavsky]

Eli Zaretskii <eliz@gnu.org> writes:

> I don't understand why limit, if we assume that no program will write
> UTF-8 encoded sequences byte-byte.  What am I missing?

I wasn't assuming that, I was wondering whether it was true or not.

> In general, I'd prefer the simplest fix, as this is going to be pushed
> to the release branch, yes?

I wasn't sure about pushing to the release branch either, but yes, I
think my first patch is safer for the release branch (since it only
affects cases where we are currently signaling an error).

Gemini, could you try it and confirm that it fixes your problem please?