Remove a lot of Results from functions. Many functions are documented to only return failing Results when given improper inputs or when there is a memory allocation failure (which can be verified by looking at the source). In cases where we know our input is correct, we don't need to check for memory allocation errors for the same reason that Rust doesn't do so when you, e.g., create a new Vec.

FROM docker.io/debian:stable

RUN apt-get -y update \
    && apt-get -y upgrade \
    && apt-get install -y cargo mercurial wget build-essential \
    && apt-get clean