Both the S6 and the S6 Edge were updated.
I think @petefoth made an honest mistake here.
Make sure to flash the correct version : @mxlx, you seem to have the S6 (Zerofltexx), not the S6 Edge (Zeroltexx).
Here’s the updated S6 unofficial Oreo build.
However, @Forumsnutzer tried flashing this unofficial S6 Oreo build, but it does not seem to go beyond the boot screen animation as can be seen in this comment. Newset 0.9 build update for Samung Galaxy S6 - is it safe now?
I suppose @Forumsnutzer did a clean flash (In TWRP, go to Wipe>Format data, then Advanced wipe>select cache and system partitions), but just in case he/she didn’t, you could try it yourself and see what happens.