In the docker image: clone delta repo and install rust toolchain

Author: dandavison

etc/docker/ubuntu.Dockerfile

@@ -3,6 +3,10 @@ FROM ubuntu:latest
 RUN apt-get update && \
     apt-get install -y curl git less
 
+RUN git clone https://github.com/dandavison/delta.git
+
+RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
+
 RUN curl -OL https://github.com/dandavison/delta/releases/download/0.8.3/delta-0.8.3-x86_64-unknown-linux-musl.tar.gz && \
     tar -xzvf delta-0.8.3-x86_64-unknown-linux-musl.tar.gz