[BUG] forking a shader that was forked via shadertoy missmatch the fork link

[FabriceNeyret]

this occurred here: https://www.shadertoy.com/view/MXVGW3
the guy forked a shader that was forked via shadertoy fork feature.
as a result, the shadertoy fork link is now set to some random URL.

suggestion: even better than keeping the original fork link, you could use the currently forked link ;-)