windows failure in testsuite

[Simon Peyton Jones]

Windows and testsuite folk: The testsuite framework is crashing on my 32-bit Windows machine, with the error below.  Happens when the stderr output differs from expected.
I know that there have been recent changes in the testsuite stuff.  Could you fix please?
Thanks
Simon
=====> T4254(normal) 1587 of 4522 [2, 15, 0]
cd ./indexed-types/should_fail &&  "C:/code/HEAD/inplace/bin/ghc-stage2.exe" -c T4254.hs -fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -rtsopts -fno-warn-tabs -fno-ghci-history   > T4254.comp.stderr 2>&1
Actual stderr output differs from expected:
'diff' is not recognized as an internal or external command,
operable program or batch file.
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