r20948 introduced 2 problems:

1) Old symlinks are no longer removed.. the "if exists" check that was added
does not account for the baseDir, so it always thinks the symlink does not
exist. Creation of the symlink then fails because of the conflict with existing
link. (this applies to overwrite of "latestStable", "latestSuccessful" links, etc.)

2) Creation of symlinks via PosixAPI does not work because it does not account
for the baseDir.