> > make check-world passed after applying this patch.
v2 changes the places of Assert, which is missed in v1 by mistakes.
I'm not an expert in this end of the code but it looks correct to me, my only comment would be maybe add a new function detoast_external_expanded_attr that is called from both detoast_external_attr and detoast_attr so the EOHP stuff stays hidden behind a function.
If that's too much API commitment then I'm fine with the way it looks inlining the EOHP code as you have to avoid the duplicate checks.