Here's a tip:
When a new update is released that you do not want to upgrade to, hit download and install yourself that same day the update is released (the idea is to do it before iOS fetches an update and downloads it automatically).
As soon as the download starts, go to Storage and select the update and delete it. This will let iOS know you do not want the update downloaded, and will also prevent issues like these.
Additionally, this means that you won't get an annoying badge app icon in Settings prompting you to update. However, this needs to be done with every update.
I use this technique to stay on 8.4.1.