bug#45058: Duplicate inputs with Crate importer

[Nicolas Goaziou]

Hello,

I noticed the Crate importer sometimes returns duplicate inputs. For
example

    guix import crate bat

returns

    ...
    (arguments
      `(#:cargo-inputs
        (("rust-ansi-colours" ,rust-ansi-colours-1)
         ("rust-ansi-term" ,rust-ansi-term-0.12)
         ("rust-atty" ,rust-atty-0.2)
         ("rust-clap" ,rust-clap-2)
         ("rust-clap" ,rust-clap-2)
         ...

Regards,
-- 
Nicolas Goaziou