build-ts: keep a package homepage that points outside the repository (0.86.9) (#34)

* build-ts: keep a package homepage that points outside the repository

orderPackageJson derived homepage from repository.url on every build, so a
package could not link its npm page to its API reference: the build put the
repository readme back and the clean-tree check failed. A homepage inside the
repository, or none, is still derived as before.

* Release dev, dev-test and dev-ts together as 0.86.9

packages/dev/scripts/util.mjs

@@ -146,6 +146,24 @@ export function engineVersionSplit (ver) {
   return [parseInt(parts[0] || '0', 10), parseInt(parts[1] || '0', 10), parseInt(parts[2] || '0', 10)];
 }
 
+/**
+ * The homepage written into a package.json. One the author pointed outside the
+ * repository (an API reference, a product site) is kept; anything else, and an
+ * absent one, is derived from the repository.
+ *
+ * @param {string} repoBase e.g. https://git.example.org/owner/repo
+ * @param {string | null} dir package directory under packages/, null for the root
+ * @param {string} [current] the homepage the package.json carries now
+ * @returns {string}
+ */
+export function packageHomepage (repoBase, dir, current) {
+  const inRepo = !current || current === repoBase || current.startsWith(`${repoBase}/`) || current.startsWith(`${repoBase}#`);
+
+  return inRepo
+    ? `${repoBase}${dir ? `/tree/master/packages/${dir}` : ''}#readme`
+    : current;
+}
+
 /**
  * Process execution
  *