Packaging git submodule as multi upstream tarballs?

[Daniel Gröber <dxld@darkboxed.org>]

Hi Mentors,

I'm working on packaging prjtrellis[1] which has a git submodule that is
required for building. My plan is to use dpkg-source's multi upstream
tarball support to do this.

[1]: https://github.com/YosysHQ/prjtrellis

I'm wondering if a) this is a good idea and 2) how to get uscan to download
the precise commit referenced in the main package instead of the "latest"
version. Is this even possible?

I have a similar situation in my yosys package already (it has a
berkeley-abc submodule) but since berkeley-abc is just a seperate package I
just package the latest berkeley-abc commit and pray it doesn't diverge
from what upstream's release uses too much. This is less than ideal
obviously.

Any input would be appreciated,
--Daniel