Shareable link should be different each time

To reproduce:

1. Get a shareable link for a picture ("make public and copy link to clipboard" grey icon)
2. Share it by mistake to the wrong person.
3. Remove the public link (click again on the icon)
4. Wrong person cannot access the picture
5. Get a shareable link for the same picture — creates same link as before
6. Share it with the right person
7. The wrong person has now access to the picture (as well as the right person)

The public link should be random and should be different each time a picture is made public.

(Edit: reproduced at the demo instance demo2.librephotos.com)