This is fantastic info, I only wish I had read it a few days sooner. But alas, I find myself here again... Does anyone have the 10.0.43 reserve.img?
Hopefully, with these instructions, I won't have to come back for .44
One thing to add, it's no longer safe to use "Install to Inactive Slot (After OTA)" at all. Using it will now cause OTA upgrades to always fail.
If you use it after taking/installing the OTA but before rebooting, the update will now fail. I'm not sure exactly when they changed this, but according to the update logs, now during an update it verifies the checksums for all partitions (including boot) twice. Once during installation of OTA, and now again on first boot after OTA install. Because of this, using "Install to Inactive Slot (After OTA)" will result in the update failing upon rebooting and the phone reverting back to boot from the older version before OTA (by auto switching the active boot slot to what it was before the OTA)