Links are not preserved when a link to an anchor is copied and pasted

[joolee]

Steps to recreate:

1. Create an anchor.
2. Create a link to that anchor.
3. Go to Source mode and come back to Design mode.
4. Select the new link to anchor. Copy and paste to another place in the editor.
5. Double click the link to edit it.

You'll see that the Link Type becomes "URL" not "Link to anchor in the text."

When <a href="#one">link to anchor</a> is copied, <a href="demo#one">link to anchor</a> is pasted.

The reason for step 3 is to get around bug #6641.