Stefan Kangas suggested I resend this patch to this mailing list so that
it's not lost even though it can't be applied yet.

Joseph Turner <joseph@breatheoutbreathe.in> writes:

> Might make sense to merge this into 29.2?
>
> [2. text/x-diff; 0001-project.el-Use-list-of-strings-p-for-safe-local-vari.patch]...