How can I ignore a package that is not in the Debian apt cache?

[m-roberts]

I am trying to package python-sonic (which depends on python-osc) for use on pi-topOS.

python-osc isn't available on Debian, and so python-sonic fails to build - it can't find the package dependency.

Given that we intend to provide both of these packages in our apt repository, we would like an easy way to override this behaviour and continue with the build. Have I missed something or is this a feature to be added?

It would be great to have a command-line argument to override this behaviour.

[m-roberts]

Turns out the wheel for this was needed at build time. This could be better documented, but I accept that the software is technically working in a reasonable way.