The Android 5.0 Nexus rollout had a little problem yesterday when a WiFi battery drain bug almost put a halt in the rollouts. Most Nexus devices were delayed in updates and another speculated release date was November 12th. That is no longer the case as the bug was quickly fixed and updates have restarted rolling out.
It appears that users experienced the problem firsthand as their devices kept waking up rather frequently when WiFi was turned on, which meant Miscellaneous began rocketing to the top of the battery use menu. It appears that, in some cases, the bug is draining up as much as 60-70% of the battery and in some cases the drainage gets to 100%.
Google managed to defuse the bomb and the bug is marked as fixed in the Issue Tracker.
Source: Google Issue Tracker