Can't build older compiler

I tried to build an up-to-date HEAD (ghc-6.9.20080920) with ghc-6.10.0.20080921 (from the release candidate tarball), and got the following error. I have double-checked that building HEAD with ghc-6.8.3 still works for me.

Building ghc-bin-6.9.20080920...

In file included from Main.hs:14:0: 

/usr/local/lib/ghc-6.10.0.20080921/ghc-6.10.0.20080921/include/HsVersions.h:23:0:
     error: ../includes/ghcautoconf.h: No such file or directory
make[2]: *** [build.stage.1] Error 1
make[1]: *** [build.stage.1] Error 2
make: *** [stage1] Error 1

My installed layout explains the error a little:

/usr/local/lib/ghc-6.10.0.20080921//ghc-6.10.0.20080921/include/HsVersions.h
/usr/local/lib/ghc-6.10.0.20080921//include/ghcautoconf.h

Although I wonder whether the root cause of this problem is that Main.hs is using the installed HsVersions.h instead of the local compiler/HsVersions.h.

Trac metadata

Trac field	Value
Version	6.9
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	MacOS X
Architecture	x86