The bug

When breaking a block with an enchanted book with Silk Touch on it, the broken block will drop as itself, as if the enchanted book was a tool other than a shovel or pickaxe.

This is unexpected, as the enchantment on books did not actually have any effect when using the book itself in previous versions, and is stored in the StoredEnchantments NBT tag instead of the tag that is used for "proper" enchantments.

Also, when breaking ice with such a book, it leaves water behind. Normally, when breaking ice with silk touch, it would always leave air behind.

To reproduce

1. Get a silk touch book
2. Break an ice block
   → The ice block drops, and in its place is a water source

Original description

Setup: Get an ice block in the world and hold an enchanted book with Silk Touch. Be in Survival Mode. Break the ice block.
Expected behavior: Either the ice block is replaced with water or the ice block drops as an item.
Observed behavior: The ice block is replaced with water and drops as an item.