SVN copy certain subdirectories to a branch

There was always a problem for me to copy only certain directories from one branch to another.
For example we have following directory structure:

trunk
      - project1
      - project2
          -subdir1
          -subdir2
          -subdir3        

We want to copy only subdir2 to a branch /branches/branch1 with saving all the structure of projects.

branches/branch1
      - project1
      - project2
          -subdir2

We want to copy only subdir2 to a branch /branches/branch1 with saving all the structure of projects.

Such a manipulation is required if you want to make a private branch for outsorcer and you don't wan him to see the other parts of the code. However you want to support reintegration of the branch back to the trunk.

The solution is 

svn cp --parents ./project2/subdir2 http://repo.url/branches/branch1/project2/subdir2

or

svn cp --parents http://<svn_path>/trunk/project2/subdir2 <working copy path>/branches/branch1/project2/subdir2

Subversion creates all intermediate directories.