Bug#1098702: apt-get --with-source crashes with Assertion '__n < this->size()' failed.

[David Mandelberg]

I found a workaround for my use case. In 
https://github.com/dseomn/dotfiles/commit/d6025819bb0fc1ffe98cdc218890f0317bea5202 
I switched from using --with-source with a Packages file, to using it 
with the .deb files directly. No idea why that fixes the issue, but it 
works for me.