[Pkg-rust-maintainers] Bug#963916: rust-debcargo: Cannot build debcargo

[peter green]

> 
> I cannot build debcargo currently. It fails with:
> 
>     missing:
>      pkg:
>       package: sbuild-build-depends-main-dummy
>       version: 0.invalid.0
>       architecture: amd64
>       unsat-dependency: librust-cargo-0.43+default-dev:amd64
> 
> Thanks
> Sylvestre

The root cause (or at least one of the root causes) of this is that rust-im-rc is stuck in new.