Microsoft has released a patch for Windows 10 build 9879 and you can download it now by going to Windows Update. The patch is being called the 'November Update' and is KB3019269.
This patch is likely why Microsoft delayed the rollout of 9879 to the slow ring; Microsoft had originally said that 'slow' ring users would get the build late last week but it was delayed until early this week. While 'slow' ring users have not yet received 9879, seeing that this patch is now out, we would expect those users to get their hands on the build very soon.
The update fixes the 0xAB bluescreen that some 'fast ring' users were hitting. Microsoft also said that they want to see how this fix plays out before pushing down the build to the 'slow' ring users.
Thanks for the tips Greg, Mike and everyone else!