[oe] force build from mirror only ?

[Frans Meulenbroeks]

I was wondering if it is possible (and what needs to be done) to fore
a build from a mirror only (or without a mirror and only using
downloads) without disconnecting from the network.
Rationale: I want to make all sources for an image available on the
mirror (including git tarballs etc) so it can be used as a reference
on where to find the opensource components for this image.

Anyone a suggestion?

Thanks! Frans