When the commit quorum is turned on for the index build, the primary will always wait for secondaries "ready to commit" votes before committing the index build. Since the index build was built on local collection, we don't replicate the startIndexBuild oplog entry to secondaries. As a result, secondaries won't be able to build the index build and participate in voting process. This can lead to index build on primary to get hang forever.

I would expect this ticket to make sure that index build on local db collections/non-replicated databases should not use commit quorum. And, should throw an error to user if the user tries to run createIndexes cmd on non-replicated databases with commit quorum options set.