Fix handling of symbolic links

Copy the symlink itself instead of its content.

Signed-off-by: Jan Blunck <jblunck@infradead.org>
Fix handling of symbolic links on cleanup

Lets simplify this and use shutil.rmtree() to replace our buggy
implementation (which failed when cleaning up broken symlinks) with a
library call.

Signed-off-by: Jan Blunck <jblunck@infradead.org>