[Pkg-rust-maintainers] rust built-using issue.

[Peter Green]

A raspbian repo update was recently snarled up due to the following built-using line for our debcargo package.

Built-Using: rust-im-rc (= 13.0.0-1+b1), rust-sized-chunks (= 0.3.1-1), rustc (= 1.35.0+dfsg1-1+rpi1)

Built-Using lines are supposed to use source package names and version numbers. However it seems that whatever generated the built-using line, correctly used the source package name "rust-im-rc", but incorrectly used the binnmu version "13.0.0-1+b1".

This should probablly be a bug report, but i'm not sure which package is responsible for generating built-using entries for rust packages.