metalsmith.js - workaround metalsmith bug in persistent env

Basically we need to reset all the metadata or we get the news pages
appended to collections.

https://github.com/segmentio/metalsmith-collections/issues/27

metalsmith.js

@@ -83,7 +83,13 @@ function elideMeta(meta) {
     };
 }
 
-module.exports = Metalsmith(__dirname)
+// We return a function building the metalsmith object.
+// This works around a metalsmith bug when run in a persistent environment.
+// https://github.com/segmentio/metalsmith-collections/issues/27
+// Another solution here:
+// https://destinmoulton.com/blog/2018/metalsmith-collections-solving-the-duplication-bug/
+module.exports = () => {
+    return Metalsmith(__dirname)
     .metadata({
         // These defaults can be overridden in pages
         sitename: "Social Coop",
@@ -124,10 +130,11 @@ module.exports = Metalsmith(__dirname)
     }))
     .use(forFiles((d,f) => buildlog.silly(f,elideMeta(d))))
     .use(assets());
+};
 
 if (require.main === module) {
     // Called directly, build
-    module.exports.build(function(err) {
+    module.exports().build(function(err) {
         if (!err) return;
         console.error('Build failed: '+err);
         process.exit(1);

serve.js

@@ -42,7 +42,7 @@ var fileOptions = {
 
 async function build() {
     buildlog.info('starting build...')
-    metalsmith.build(function(err) {
+    metalsmith().build(function(err) {
         if (err)
             buildlog.error('build exception', err);
     })