-Wincomplete-record-updates not working since 9.6

Summary

Between 9.4 and 9.6 the -Wincomplete-record-updates flag seems to have been removed. I was not able to find anything on that in the release notes either.

Steps to reproduce

Try to compile this code with -Wincomplete-record-updates

module MyLib where

data T = T1 { x :: Bool } | T2

f a = do
  a { x = False }

in 9.4, a warning is thrown, but in 9.6 it's not