Within the past hour, Microsoft released a new patch, KB 3025380, for Windows 10 Technical Preview testers. The update is available for build 9879. It doesn't appear to be available for the pirate build 9901.
What does the update do, precisely? Good question. Microsoft spokesman Gabe Aul tweeted:
Hi #WindowsInsiders - one more WU update today. This one preps your system to take the next build from FBL_AWESOME branch.
As Aul explained yesterday, the FBL_AWESOME branch is the branch that will be distributed on or about January 21:
just so that we have a *daily* reminder to ourselves that we want this build to be great, we even named our build branch FBL_AWESOME. Yeah, it’s a bit corny, but trust me that every Dev that checks in their code and sees that branch name gets an immediate reminder of our goal.
The KB 3025830 article itself doesn't give many details:
This update includes improvements to Windows 10 Technical Preview Build 9879 that will let members of the Windows Insider Program to continue to receive future released builds of Technical Preview.
It looks like the patch simply changes both the "Fast" and "Slow" testers so their next update comes from the new branch -- like a merging of the firehoses, metaphorically.
If you learn more, please hit me in the comments.