scoped type variables in instance?

[Ross Paterson]

I wrote:
> | OK, I see this was intentional:
> | 
> | 	"The type variables in the head of a class or instance 
> | 	declaration scope over the methods defined in the where part."
> | 
> | But both provisions cause Haskell 98 modules to be rejected, 
> | even without -fglasgow-exts. 

On Mon, Apr 22, 2002 at 07:38:09AM -0700, Simon Peyton-Jones wrote:
> That's a bug; I'll fix it.

Is rejecting Haskell 98 modules when -fglasgow-exts is on also a bug?
(i.e. does GHC Haskell aim to be a conservative extension of H98?)