[Dbix-class] ANNOUNCE: 0.08121 -- add_to_$rel broken with objects

[Peter Rabbitson]

Ashley wrote:
> Hijacking the announce thread.
> 
> add_to_$rel no longer seems to support adding objects. Only hashrefs.
> Was this intentional or a regression bug? It was working in recent
> versions and is still documented to work in the Pod. I haven't dug
> deeply into this but an app of mine broke on this upgrade. Not sure what
> DBIC version it was on before but it wasn't tooooo old.
> 

Details:

1) the *exact* add_to_$rel invocation
2) the definition of $rel / $rel_class
3) the actual error taking place
4) version where it worked (yes it matters)