"No child processes" in 6.6-candidate

[Serge D. Mechveliani]

Dear GHC developers,

Sometimes  ghc-6.6-candidate  reports

--------------------------------------------------
runhaskell Setup.hs install --user
...
*** Exception: waitForProcess: does not exist (No child processes)
--------------------------------------------------

under  Linux.

This happens as follows.

I build my large project (it uses Cabal, and it has some import loops)
and install it.
Then, I edit a bit, for example, the source module  Dumatel.KBC,
remove by  rm -rf  all the files from the installation directory  
./inst/,  
and command   make build         (runhaskell Setup.hs build)
              make install       (runhaskell Setup.hs install --user).
It reports
---------------------------------------------------
scico:~/dm/1.06/dm/source> make build
runhaskell Setup.hs build
Preprocessing library dumatel-1.6...
Building dumatel-1.6...
[10 of 38] Compiling Bool0[boot]  ( Bool0.hs-boot, nothing )
[22 of 38] Compiling Dumatel.KBC  ( Dumatel/KBC.hs, dist/build/Dumatel/KBC.o )
/usr/bin/ar: creating dist/build/libHSdumatel-1.6.a

(looks all right: it re-compiles only the changed module and something
which also may be necessary)

scico:~/dm/1.06/dm/source> make install
runhaskell Setup.hs install --user
Installing: 
/home/mechvel/dm/1.06/dm/source/inst/lib/dumatel-1.6/ghc-6.5.20060831 & 
/home/mechvel/dm/1.06/dm/source/inst/bin dumatel-1.6...
*** Exception: waitForProcess: does not exist (No child processes)
make: *** [install] Error 1
------------------------------------------------------------------

ghc-6.4.1  did `install' all right in approximately the same situation
           (the source modules where a bit different).

Then, I remove all the files also from the `build' directory 
./dist/  and do by new `build' and `install'. And then, it works.

The matter is that compiling all modules by new slows down the process
of developing a project.

Can the above effect present a bug in the  ghc + Cabal  system?

-----------------
Serge Mechveliani
mechvel at botik.ru