__setstate__ with 'partial' keep_alive

[adedner]

Issue:
In an example setter I get a pybind11:list with two entries, the first has to be kept alive the other arguments need to be garbage collected (large bytestream that I copy).

Description:
I figured out that I can add keep_alive<1,2> to the extra flag (that will be correctly added to the setter) but I'm assuming this will keep all entries in the list alive. Is there any workaround for this?
In other cases I used weakref and my own ref counting as mentioned in the documentation but here I don't have access to the pybind11::object self to use to setup the weakref. Is there some way of only keeping certain objects in the list alive?

I tried calling something like pybind11::handle/object h = t[1]; h.dec_ref() but that segfaulted.

Thanks for any help!