This broke Windows 10 version 1607. I run it at home, and at work on a couple of test desktops, but i know of no instances of 1607 under our SCCM - for that matter, we only have about a 5% deploy of Windows 10.
So yes, this slipped through, but I think the actual exposure will be quite small. Lots of crowds and torches on slashdot, but this is probably a very small blip.
In fact, by virtue of how Fast Track gets deployed I don't think I'd ever see this issue -
Win10 install from SCCM or ISO
Apply DSC config as part of the build or part of a configuration script
manually enable fast track
wait for MS to update the box to fast track
get the new build
finally get the bad patch
If I were MS, I'd look at creating a better patch/update exposure matrix - the Fast Track for Insider Updates includes all sorts of telemetry, and I would imagine that they could look at a patch and compare the functionality to the actual use telemetry - "This patch updates DSC. DSC has been used by 1% of all fast track users over the past 10 days. Risk of patch++"