[Law] Rolling the ball forward

[VM75]

Bit of a strange, entirely theoretical question I was asked yesterday:

If a player were to place the ball on the ground and roll it forward once it's already there, what would you do?

He was arguing that it wasn't technically a knock on.

My thoughts were that it was some sort of infringement, the only question being whether it's a scrum or a penalty.

11.7 [FONT=fs_blakeregular]A player must not intentionally throw or pass the ball forward.
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Rolling it forward is essentially a Forward Pass (albeit a bad or ineffective one), if it's not, then what stops anyone rolling it forward to a teammate ahead of them.