It took me long enough to realise that I hadn't saved the test image
after loading FileSystem, thus leaking a process and borking the
build, but realise it I did. Lo and behold, we have a CI build for
FileSystem, showing 5 test failures:

http://build.squeak.org/job/ExternalPackage-FileSystem/7/

FS.Tests.Core.FSPlatformResolverTest.testDesktop
FS.Tests.Core.FSPlatformResolverTest.testDocuments
FS.Tests.Disk.FSDiskFilesystemTest.testCopy
FS.Tests.Disk.FSFileHandleTest.testIncomplete
FS.Tests.Disk.FSFileHandleTest.testReadBufferTooLarge

IIRC the first two fail because of platform issues or assumptions
about from which directory Squeak is being run, and the last three are
because of references to Xtreams.

I don't mind things depending on Xtreams - I really, really like
Xtreams - but from a aim-for-minimal-image perspective it's bad. Or,
to put it another way, I'd be fine with replacing Streams with
Xtreams, but that's far too much to do in 4.5.

frank