Fix windows endline breaking shebang.

Dockerfile

@@ -4,5 +4,6 @@ ADD package.json .
 RUN npm install --production
 ADD check-some-are-unignored.sh .
 ADD check-vcs-changes.sh .
+RUN sed -i -e 's/[\r]//g' ./check-*.sh
 RUN chmod +x ./check-*.sh
 ENTRYPOINT /work/check-vcs-changes.sh