Install/remove build-essential during build so we can install the recommended packages from Git.

Dockerfile

@@ -3,13 +3,13 @@ FROM debian:sid
 ARG DEBIAN_FRONTEND=noninteractive
 
 RUN apt-get update && apt-get dist-upgrade --yes
-RUN apt-get install --yes --no-install-recommends devscripts equivs
+RUN apt-get install --yes --no-install-recommends build-essential devscripts equivs
 
 ADD [".", "/srv/diffoscope"]
 RUN mk-build-deps --install --tool 'apt-get -o Debug::pkgProblemResolver=yes --no-install-recommends --yes' /srv/diffoscope/debian/control
 
-RUN apt-get remove --purge --yes devscripts equivs
-RUN apt-get autoremove --purge --yes
+RUN apt-get remove --purge --yes build-essential devscripts equivs
+RUN rm -rf /srv/diffoscope/debian
 
 RUN useradd -ms /bin/bash user
 USER user