Does its job, but complains about an error and exits with an error code.

---
$ mkdir dir; touch src; ln -s --target-dir=dir ../src; echo $?; ls -l src dir
ln: `dir/.\': cannot overwrite directory
1
-rw-r--r--    1 imz      imz             0 Окт  8 00:36 src

dir:
итого 0
lrwxrwxrwx    1 imz      imz             6 Окт  8 00:36 src -> ../src
[<a href="mailto:imz@basalt" target="_new">imz@basalt</a> tmp]$ rpm -qf /bin/ln
coreutils-4.5.1-alt2
[<a href="mailto:imz@basalt" target="_new">imz@basalt</a> tmp]$

---
Putting \&quot;dir\&quot; as the last argument makes it work.

Similar 

cp --target-dir=dir src

works fine.

This:

cp --symbolic-link --target-dir=dir \&quot;$(pwd)\&quot;/src

also works; can be regarded as a workaround.