I failed to document the new behaviour in the docstring.

The patch I sent didn't manage the creation of the new symlink correctly
either, as it created it with the same name as the target.  That is, in
the examples given the result was:

-------------------------
(copy-directory "~/tmp/foo" "~/Test" nil t)
=>
[mcenturion@localhost ~]$ ls -l Test
total 4
lrwxrwxrwx. 1 mcenturion mcenturion 26 ago 19 21:21 Test1 -> /home/mcenturion/tmp/Test1
-------------------------

This new patch corrects both mistakes.

Sorry for the misfire.