This finally made the Windows buildslave get its act together. It now builds
darcs and runs tests. A bunch fails, with following error:

darcs.exe: DeleteFile: permission denied (The process cannot access the file because it is being used by another process.)

Vast majority of these is in check (and maybe repair), plus at least one in
optimize --compress. I suppose all of these are because it's trying to delete a
file that it didn't close, which fails on windows (I wish I knew why...).

Moreover, there seems to be a bug in ShellHarness, since only a subset of
failed tests is printed near the end. I guess that should be filed separately,
or fixed right away (I haven't looked yet why that could be though).

Yours,
   Petr.

Salvatore had sent a message to the mailing list suggesting that this may not
even be our bug, but something Windows related.

We're a little bit stuck on this because we can't reproduce this failure
anywhere else but on the build slave.

I've filed a separate bug http://bugs.darcs.net/issue1428 for the shell harness
issue.

I believe this was fixed in darcs 2.3 by:

Tue Jul 14 14:42:32 BST 2009  Petr Rockai <me@mornfall.net>
  * Use mmapFilePS in gzReadFilePS to avoid lazy bytestring readFile.
  
  It turns out that the lazy readFile does not close the filedescriptor soon
  enough in some cases and causes DeleteFile failures on win32. mmapFilePS uses
  mmap when available and falls back to strict bytestring readFile, neither of
  which causes these issues.