Revert recent ill-advised test case changes.

Revert recent ill-advised test case changes.

Commit 6bf5c42b5546984df29289918f952e6211069c54 cannot work on Windows,
because it lacks symlink support. While the bug fix in commit
cd64dc42d1e1b03e57e6ba3d316e4f9dec52a78d is correct as far as I know,
the test case changes depend on the previous commit, so this will
have to live without test coverage until we can come up with a better
solution. Commit fa7036dd6644d13233b475874a94754a5903e35a was a test
case bug fix on top of those two, to prevent failures on Linux, so that
has to come out as well.

Per the buildfarm, CI, and Thomas Munro.