What I expected to happen was when I was breaking some cobblestone I switched from holding a blaze rod to having nothing in my hand was for the process to carry on like it did in 1.4.2.
What actually happened was it started the block breaking process again from the start.
Steps to Reproduce:
1. Place Cobblestone
2. Hold blaze rod
3. Start to break cobblestone
4. Switch to hand
Linked issues
Comments 4
Duplicate of MC-2519
dublicate of MC-2519
pleas note that this is intended behavior. like dalton said, it was possible to avoid damage-costs on e.g. pickaxe this way.
//edit: someone was quicker than me 🙂

Duplicate of MC-2519. Please check before posting in the future.
I think this is unfortunately a fix for a long-time glitch of using a pickaxe to mine something quickly and switching to a dirt block last second to avoid the cost.