ln --relative broken on u14, works on u16

[Scott Mcdermott]

in ubuntu14, the behavior of "ln --relative" seems to be quite broken. on ubuntu 16 it works as expected. can we please backport whatever fix from u16 or update coreutils? 8.15 is where they started including the 'realpath' binary, maybe they fixed "ln --relative" too.

u14 INCORRECT:

$ loop=0; nloops=4; base=/tmp/lntest; rm -rf $base/ && mkdir -p $base/dir &&
touch $base/dir/file && while ((loop++ < nloops)); do ln -frs $base/dir/file $base/link; readlink -f $base/link; sleep 1; done
/tmp/lntest/dir/file
/tmp/lntest/file
/tmp/lntest/dir/file
/tmp/lntest/file

u16 CORRECT:

$ loop=0; nloops=4; base=/tmp/lntest; rm -rf $base/ && mkdir -p $base/dir &&
touch $base/dir/file && while ((loop++ < nloops)); do ln -frs $base/dir/file $base/link; readlink -f $base/link; sleep 1; done
/tmp/lntest/dir/file
/tmp/lntest/dir/file
/tmp/lntest/dir/file
/tmp/lntest/dir/file