Put the summary of the bug you're having here
When you place a Slightly Damaged or a Very Damaged Anvil they revert back to a regular Anvil

What I expected to happen was the Slightly Damaged Anvil to remain Slightly Damaged and not to go back to regular

What actually happened was the Slightly Damaged Anvil reverted to a normal anvil.

Steps to Reproduce:
1. Use an Anvil to repair, crush someones head, name, etc.
2. Break with a pick ax
3. Place again
4. Pick back up, now full use anvil.