I think this is wrong. Isn't it `ln source file, new target`?

```
[0] moses@mosesmac:subdir$ ls -lia
total 0
13647711 drwxr-xr-x  3 moses  staff  102 Apr 18 07:33 .
13647703 drwxr-xr-x  3 moses  staff  102 Apr 18 07:33 ..
13647705 -rw-r--r--  1 moses  staff    0 Apr 18 07:32 foo
[0] moses@mosesmac:subdir$ ls -lia ..
total 0
13647703 drwxr-xr-x   3 moses  staff  102 Apr 18 07:33 .
 9236843 drwxr-xr-x  15 moses  staff  510 Apr 18 07:32 ..
13647711 drwxr-xr-x   3 moses  staff  102 Apr 18 07:33 subdir
[0] moses@mosesmac:subdir$ irb
irb(main):001:0> require 'FileUtils'
=> true
irb(main):002:0> FileUtils.ln('..', 'foo')
Errno::EEXIST: File exists - (.., foo)
	from /usr/local/Cellar/ruby/2.0.0-p247/lib/ruby/2.0.0/FileUtils.rb:310:in `link'
	from /usr/local/Cellar/ruby/2.0.0-p247/lib/ruby/2.0.0/FileUtils.rb:310:in `block in ln'
	from /usr/local/Cellar/ruby/2.0.0-p247/lib/ruby/2.0.0/FileUtils.rb:1567:in `fu_each_src_dest0'
	from /usr/local/Cellar/ruby/2.0.0-p247/lib/ruby/2.0.0/FileUtils.rb:308:in `ln'
	from (irb):2
	from /usr/local/bin/irb:12:in `<main>'
irb(main):003:0> FileUtils.ln('foo', '..')
=> 0
irb(main):004:0> exit
[0] moses@mosesmac:subdir$ ls -lia ..
total 0
13647703 drwxr-xr-x   4 moses  staff  136 Apr 18 07:34 .
 9236843 drwxr-xr-x  15 moses  staff  510 Apr 18 07:32 ..
13647705 -rw-r--r--   2 moses  staff    0 Apr 18 07:32 foo
13647711 drwxr-xr-x   3 moses  staff  102 Apr 18 07:33 subdir
[0] moses@mosesmac:subdir$
```