Extend the copy stage to optionally allow removing the destination
before copying. This allows one to not follow symlinks if the
destination is a symlink to a file. By default, `cp` would change
the file pointed to by the destination if it is symlink.
Extend the stage doc text to cover the behavior with regard to
destination being a symlink.
Add unit tests for the copy stage to also test the newly added option.
Signed-off-by: Tomáš Hozza <thozza@redhat.com>
200c2b0129