In general, you're asking for trouble ;-) Try to refrain from changing the content of the thing you're currently iterating. For instance, if you mess with the indexes instead of the data you would see very strange results.

I would suggest letting the dump finish, and store the new values back:

Got it!

As an aside, holy shit I had no clue zl.group functioned like that without an argument. That's huge! I've been using lin all these years and no one has it. indispensable functionality.