Ensure synced with upstream/master

Author: codebytere

lib/promote_release.js

@@ -323,6 +323,9 @@ class ReleasePromotion {
     const releaseCommitSha = this.getCommitSha(1);
     runSync('git', ['checkout', 'master']);
 
+    // Pull master from upstream, in case it's not up-to-date.
+    runSync('git', ['pull', '--rebase', 'upstream', 'master']);
+
     // There will be conflicts.
     runSync('git', ['cherry-pick', releaseCommitSha]);
   }