Bug#920958: rust-ripgrep build-dependencies unsatisfiable in testing
> The following packages have unmet dependencies:
> builddeps:rust-ripgrep : Depends: librust-bytecount-0.3+default-dev (>= 0.3.1~~) but it is not installable
> Depends: librust-memmap-0.6+default-dev but it is not installable
This appears to be fixed in unstable, but unfortunately there are other issues preventing unstable's version from migrating to testing.