This is not a bug, but feature request.

Expected

Digging Turtle changes Grass Block into Grass Path Block with turtle.dig() function.

Actual

The Turtle returns false in the above situation.

Detail

From 1.9, "Grass Path" block is added. It can be created from Grass block by right clicking with Spade.
So, naturally, Digging Turtle should create Grass Path block from Grass block by dig() function as Farming Turtle can create Farmland block.

(And now, a player make Grass Path block change into Farmland block by right clicking with Hoe...)

I think this would make sense but only if it were Digging Turtles (with shovels) that can make grass paths. It would also give them a use over the all-powerful Mining Turtles.

Ah! I just mistook Digging Turtle and Mining Turtle! Digging Turtle is correct. I edited original replay...
Thanks!

Do the above commits warrant this closed?

No - I haven't put forward a PR because I'm not happy with either of those commits. There are still a couple of things about the existing implementation that I'm not sure about, namely:

• Hoeing/shovelling dirt will attempt to transform the block one block away, two blocks away and one block away and then down. This makes sense for turtle.place() but not here - I think it would be better if it just did one block away and one block away and down (which allows for hoeing/shovelling the block below you).
• TurtlePlaceEvent.deploy is too general for the tool - technically turtle.dig() with a hoe/shovel will also attempt to right click entities in front of it, as well as triggering block's own right click methods. Ideally it would call just the sufficient methods to hoe/flatten dirt.
• PlayerInteractEvent.RightClickBlock is not fired. There are mods which allow the shovel to convert normal dirt to path blocks, using this event. Firing it would allow these mods to function as expected.

@dan200 My second attempt at this (SquidDev-CC/ComputerCraft@93aea37) does that. However, there are a couple of things I'm not sure about, as mentioned in my previous comment. I'm happy to PR it though if you're OK with it as is.

I would be happy to merge that PR. It's better for the rules to be Consistent with placing and hoeing than not.