Why is the bibfiles cache sorted?

[Jürgen Spitzmüller]

Riki,

In Buffer::updateBuffer(), we sort the bibfiles cache:

    sort(d->bibfiles_cache_.begin(), d->bibfiles_cache_.end());

(Why) Is this necessary?

I am asking since Biblatex uses getBibFiles in order to output the
\addbibresource lines in the preamble. These should be order according to
the order in the BibTeX inset, however, not alphabetically (the order
matters).

Commenting out fixes this problem for Biblatex, but what is the reason of
the sort in the first place?

Jürgen