fix: unset GHE token before checking node releases

Fixes #1540

lib/manager/npm/engines.js

@@ -13,11 +13,27 @@ async function renovateEngines(config) {
     logger.info({ currentVersion }, 'Skipping non-pinned node version');
     return [];
   }
+  let endpoint;
+  let token;
+  // istanbul ignore if
+  if (process.env.GITHUB_ENDPOINT) {
+    logger.debug('Removing GHE token before retrieving node releases');
+    endpoint = process.env.GITHUB_ENDPOINT;
+    delete process.env.GITHUB_ENDPOINT;
+    token = process.env.GITHUB_TOKEN;
+    process.env.GITHUB_TOKEN = process.env.GITHUB_COM_TOKEN;
+  }
   const newReleases = (await getRepoReleases('nodejs/node'))
     .map(release => release.replace(/^v/, ''))
     .filter(release => semver.major(currentVersion) === semver.major(release))
     .filter(release => semver.gt(release, currentVersion))
     .sort(semverSort);
+  // istanbul ignore if
+  if (endpoint) {
+    logger.debug('Restoring GHE token and endpoint');
+    process.env.GITHUB_TOKEN = token;
+    process.env.GITHUB_ENDPOINT = endpoint;
+  }
   if (newReleases.length) {
     logger.info({ newReleases }, 'Found newer Node releases');
   } else {