The March level Android security patch has rolled out to most Nexus devices within their service life. The Nexus 6 started to get it earlier on this week, but further roll-out was canceled mid-week.
Redditors have reported that build number N6F26U on Android 7.1.1 broke the SafetyNet API that checks for things being intact on device boot — that includes the bootloader status, critical to whether Android Pay works on the device.
— Kevin Burton (@MeKevinB) March 8, 2017
The Nexus team acknowledged the issue through Twitter and have since pulled the update, only to redeploy it today. New factory images and OTAs are available with SafetyNet disabled. Android Pay theoretically can be used with or without a locked bootloader, posing security problems.