Confirmed in release 1.8
BTW, why didn't Tails confirm this?
It is irrelevant if you can generate cobblestone, this issue is that the game generates blocks that cannot be replaced in survival once broken. This should not be closed as "works as intended", atleast not in my opinion
This is impossible in vanilla survival.
This has to do with anti-aliased textures in general. This has broken a lot of texturepacks. A lot. I can only recommend reverting this change since this screws up hours and hours of work for no reason. Here is a video briefly showing how to fix it:
https://www.youtube.com/watch?v=R1GZA_x9ffs&list=UULxkLHhIjzPXGdxqeuVTgkQ