Various nether changes are leaking into old base_game worlds

Remaining issues as of 1.16.200

These issues affect old base game worlds, causing regressions. No 1.16 changes should be present in these old worlds, since content might rely on them staying the same. These are listed in no particular order of importance, though some are certainly more important than others.

Entities

• Zombie Pigmen entity name appears as "Zombified Piglin" instead of the old name. Same for their spawn egg.

• Endermen can't pick up netherrack.

Blocks

• Beacon beams merge stained glass colors.

• Flowers can be removed from flower pots.

Items

• The "snout" banner pattern item is present. It adds a missing texture overlay when used in the loom.

• Vanishing and binding curse enchantments are obtainable.

• Soul speed enchantment is obtainable.

How to reproduce

1. Acquire a world with base game version 1.13 (this task is left as an exercise for the reader)
2. Try one of the things mentioned
→ ❌ 1.16 behavior instead of 1.13 behavior

Fixed

The following behaviors have been fixed:

Unknown (tested in 1.16.200)

• Lighting soul sand on fire produces a buggy "update" dirt block

• Accessing a beacon spams the content log with a warning about netherite ingots

1.16.0.64:

• "Update block" blocks appear in the creative inventory

• Nether biomes, ores, and other 1.16 features

• Ruined portals in the overworld

• Mobs don't seem to take any knockback

1.16.0.59:

• Blank piglin and hoglin spawn eggs appear in the creative inventory