ghc-6-2-branch `internal error'

Dear GHC developers,

I have `made' GHC of   cvs update -r ghc-6-2-branch    (about May 14)

by  ghc-6.2.1   on  RedHat Linux (about version 8) libc-2.2, i686.

Now, you have the                 docon-2.08-pre  
test, with  Pol3_.hs  containing

  instance (LinSolvRing (Pol a), CommutativeRing a) =>
                                          LinSolvRing (UPol (Pol a))
  ...

And      make space=-M20m docon           
(-Onot) 
yields
   ...
   ... 
    /home/mechvel/docon/2.08/docon/source/export/Pfact3_.hi:
     openBinaryFile: does not exist (No such file or directory)
   Compiling Pfact3_ 
     ( pol/factor/Pfact3_.hs,
       /home/mechvel/docon/2.08/docon/source/export/Pfact3_.o )

   ==================== INTERFACE HAS CHANGED ====================
   No old interface available

   ghc-6.2.1: internal error: scavenge_mark_stack: 
                   unimplemented/strange closure type 30 @ 0x41692598
    Please report this as a bug to glasgow-haskell-bugs@xxxxxxxxxxx,
    or http://www.sourceforge.net/projects/ghc/


Repeating this command, or `making' it from the start under  -M30m 
avoids this report.

-----------------
Serge Mechveliani
mechvel@xxxxxxxx