Cirrus: Verify Cirrus YML determinism

Fixes https://github.com/namecoin/ncdns-repro/issues/94

tools/cirrus_build_project.sh

@@ -15,6 +15,11 @@ df -h
 lscpu
 free -m
 
+echo "Verifying Cirrus YML determinism..."
+mv .cirrus.yml .cirrus.yml.bak
+./tools/cirrus_gen_yml.sh 2>/dev/null
+diff .cirrus.yml .cirrus.yml.bak
+
 echo "Installing rbm deps..."
 APT_DEPS="libyaml-libyaml-perl libtemplate-perl libio-handle-util-perl libio-all-perl libio-captureoutput-perl libjson-perl libpath-tiny-perl libstring-shellquote-perl libsort-versions-perl libdigest-sha-perl libdata-uuid-perl libdata-dump-perl libfile-copy-recursive-perl libfile-slurp-perl git runc rsync"
 apt-get install -y $APT_DEPS || (sleep 15s && apt-get install -y $APT_DEPS)