Yes, I just had linksys auto update, update my wrt1900ac V2 with an older revision.
I was testing with ACS V1 firmware and the update changed to a version below the latest AC V2 but higher than original. So far there is no record of this version and which router model it is for, since I had ACS V1 running at the time, and all ACS V1 firmwares begin with a 1.
This is the new old firmware revision, 2.0.8.177401
The down side is that it removed Advanced Features, so i cannot change gain and other options, on the pre ACS V2 routers.
Another reason, when I get done with my testing, to go open wrt.