Does Buildout support value substitution in the extends option?

Does Buildout support value substitution in the extends option of the buildout section?

For example, this example.cfg doesn't extend with base.cfg:

[config]
base = base.cfg

[buildout]
extends =
    ${config:base}
parts =

---

buildout -c example.cfg annotate

---

My goal is to send the file-to-extend as a parameter from the outside like this:

buildout config:base=base.cfg -c example.cfg annotate

I tried to merge the buildout:extends from the outside; but that doesn't work either:

buildout buildout:extends+=base.cfg -c example.cfg annotate

from Does Buildout support value substitution in the extends option?