Try using npm proxy instead

.ci/build

@@ -7,6 +7,7 @@ fi
 export PATH="$(pwd)/hugo:$PATH"
 
 cd siterepo
+npm config set registry http://nexus:8081/repository/npm_proxy/
 ./build.sh
 rm ./hugo-static/public/manifest.json # Conflicts with main manifest.
 cp -r ./assets/* ./assets/.??* ./hugo-static/public/* ../sitegen/

build.sh

@@ -1,11 +1,9 @@
 #!/bin/bash -e
 
-# Concourse Worker doesn't support IPv6 well yet.
-function npm-ipv4() {
-    node --dns-result-order=ipv4first $(which npm) $*
-}
-npm-ipv4 install -Dy
-npm-ipv4 -y exec webpack
+npm install -g npm
+
+npm install -Dy
+npm -y exec webpack
 cp ./node_modules/xterm/css/xterm.css ./assets/
 cp dist/main.js ./assets/main.js
 cd hugo-static