RULES pragma broken in the head

This module:

module Foo where
{-# RULES "id" forall x. id x = x #-}

compiles fine with 6.8.3 but the HEAD says (twice):

Foo.hs:2:0: Unrecognised pragma

Adding -frewrite-rules has no effect. But with -XRank2Types, it compiles fine for some reason.

Trac metadata

Trac field	Value
Version	6.9
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
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Operating system	Unknown
Architecture	Unknown