Reverts 965e106f24
Unfortunately, this caused breakage on Windows, and possibly elsewhere,
because parentDir and takeDirectory do not behave the same when there is a
trailing directory separator.
parentDir is less safe than takeDirectory, especially when working
with relative FilePaths. It's really only useful in loops that
want to terminate at /
This commit was sponsored by Audric SCHILTKNECHT.
The shell code was nasty, and buggy. New haskell code is much nicer,
and it's easy to do complicated calculations to properly convert possibly
absolute symlinks between libraries into relative links using it.
