In old path redirects, freeze up sets we iterate over (#16916)

Author: heiskr

lib/redirects/get-old-paths-from-permalink.js

@@ -56,7 +56,7 @@ module.exports = function getOldPathsFromPath (currentPath, languageCode, curren
 
   // ------ BEGIN MODERN VERSION FORMAT REPLACEMENTS ------//
   if (currentlySupportedVersions.includes(currentVersion) || versionSatisfiesRange(currentVersion, `>${lastReleaseWithLegacyFormat}`)) {
-    oldPaths.forEach(oldPath => {
+    (new Set(oldPaths)).forEach(oldPath => {
       // create old path /github from new path /free-pro-team@latest/github
       oldPaths.add(oldPath
         .replace(`/${nonEnterpriseDefaultVersion}`, ''))
@@ -107,19 +107,22 @@ module.exports = function getOldPathsFromPath (currentPath, languageCode, curren
   // ------ END MODERN VERSION FORMAT REPLACEMENTS ------//
 
   // For each old path added to the set above, do the following...
+  (new Set(oldPaths)).forEach(oldPath => {
+    // for English only, remove language code
+    if (languageCode === 'en') {
+      oldPaths.add(getPathWithoutLanguage(oldPath))
+    }
 
-  // add language code
-  oldPaths.forEach(oldPath => oldPaths.add(getPathWithLanguage(oldPath, languageCode)))
+    // add language code
+    oldPaths.add(getPathWithLanguage(oldPath, languageCode))
 
-  // for English only, remove language code
-  if (languageCode === 'en') {
-    oldPaths.forEach(oldPath => oldPaths.add(getPathWithoutLanguage(oldPath)))
-  }
+    // create /enterprise from /enterprise/latest
+    oldPaths.add(oldPath.replace(`/enterprise/${latest}`, '/enterprise'))
+  })
 
-  // create /enterprise from /enterprise/latest
-  oldPaths.forEach(oldPath => oldPaths.add(oldPath.replace(`/enterprise/${latest}`, '/enterprise')))
+  // exclude any empty old paths that may have been derived
+  oldPaths.delete('')
+  oldPaths.delete('/')
 
-  return Array.from(oldPaths)
-    // exclude any empty old paths that may have been derived
-    .filter(oldPath => oldPath !== '' && oldPath !== '/')
+  return oldPaths
 }